endothelin-1 and Body-Weight

To study the association between hepatocyte growth factor (HGF) and treatment response in mice with hypoxic pulmonary arterial hypertension (HPAH) and the possibility of HGF as a new targeted drug for HPAH.. After successful modeling, the HPAH model mice were randomly divided into two groups: HPAH group and HGF treatment group (tail vein injection of recombinant mouse HGF 1 mg/kg), with 10 mice in each group. Ten normal mice were used as the control group. After 5 weeks, echocardiography was used to measure tricuspid peak velocity, right ventricular systolic pressure, right ventricular hypertrophy index, and right ventricular/body weight ratio; the Griess method was used to measure the content of nitric oxide in serum; ELISA was used to measure the serum level of endothelin-1; transmission electron microscopy was used to observe changes in the ultrastructure of pulmonary artery.. Compared with the HGF treatment and normal control groups, the HPAH group had significantly higher tricuspid peak velocity, right ventricular systolic pressure, right ventricular hypertrophy index, and right ventricular/body weight ratio (. Increasing serum HGF level can alleviate the impact of HPAH on the cardiovascular system of mice, possibly by repairing endothelial cell injury, improving vascular remodeling, and restoring the normal vasomotor function of pulmonary vessels.

Topics: Animals; Body Weight; Endothelial Cells; Endothelin-1; Hepatocyte Growth Factor; Hypertrophy, Right Ventricular; Hypoxia; Mice; Nitric Oxide; Pulmonary Arterial Hypertension

High-sugar intake may cause endothelial dysfunction. It is unknown if a bout of aerobic exercise improves endothelial dysfunction caused by a high-sugar meal in postmenopausal women. This study evaluated if prior aerobic exercise attenuates postprandial endothelial dysfunction in postmenopausal women. Twenty-two postmenopausal women (age [mean±SD]: 60.4±6.5 years; % body fat: 40.3%±7.5%) underwent an exercise (EX) or no exercise (NE) condition, in a random order, 13-16 hours prior to the high-sugar meal consumption. The EX condition included a 60 min bout of supervised aerobic exercise at 75% of age-predicted maximum heart rate. The high-sugar meal, consumed after a 12-hour fast, contained 33% of the subjects' daily energy needs, and 75.6% energy from carbohydrates. Flow-mediated dilation (FMD) and blood concentrations of glucose, insulin, endothelin-1 (ET-1), and nitric oxide (NO) were assessed at baseline and 60 min, 120 min, and 180 min postprandially. Repeated measures analysis test showed that there were no condition by time interaction or condition effects for FMD, glucose, insulin, or NO. There was a significant condition by time interaction but no condition effect for ET-1. Area under the curve was also not different by condition for insulin sensitivity or the above variables. In conclusion, prior aerobic exercise compared with NE did not affect FMD, blood glucose, insulin, ET-1 or NO concentrations, or insulin sensitivity following a high-sugar meal in postmenopausal women. Future studies should look at the effect of different EX intensities on meal-induced endothelial dysfunction in this population.

Topics: Aged; Blood Glucose; Body Weight; Cross-Over Studies; Endothelin-1; Endothelium, Vascular; Energy Intake; Exercise; Female; Humans; Insulin; Middle Aged; Nitric Oxide; Postmenopause; Postprandial Period; Vasodilation

Serum nitric oxide (NO) reduction and increased endothelin-1 (ET-1) play a pivotal role in endothelial dysfunction and hypertension. Considering that traditional Mediterranean diet (TMD) reduces blood pressure (BP), the aim of this study was to analyze whether TMD induced changes on endothelial physiology elements such as NO, ET-1 and ET-1 receptors which are involved in BP control.. Non-smoking women with moderate hypertension were submitted for 1 year to interventions promoting adherence to the TMD, one supplemented with extra virgin olive oil (EVOO) and the other with nuts versus a control low-fat diet (30 participants/group). BP, NO, ET-1 and related gene expression as well as oxidative stress biomarkers were measured.. Serum NO and systolic BP (SBP) or diastolic BP (DBP) were negatively associated at baseline, as well as between NO and ET-1. Our findings also showed a DBP reduction with both interventions. A negative correlation was observed between changes in NO metabolites concentration and SBP or DBP after the intervention with TMD + EVOO (p = 0.033 and p = 0.044, respectively). SBP reduction was related to an impairment of serum ET-1 concentrations after the intervention with TMD + nuts (p = 0.008). We also observed changes in eNOS, caveolin 2 and ET-1 receptors gene expression which are related to NO metabolites levels and BP.. The changes in NO and ET-1 as well as ET-1 receptors gene expression explain, at least partially, the effect of EVOO or nuts on lowering BP among hypertensive women.

Topics: Aged; Aged, 80 and over; Biomarkers; Blood Glucose; Blood Pressure; Body Mass Index; Body Weight; Cholesterol, HDL; Cholesterol, LDL; Diet, Fat-Restricted; Diet, Mediterranean; Endothelin-1; Female; Gene Expression Regulation; Humans; Hypertension; Life Style; Middle Aged; Nitric Oxide; Nuts; Olive Oil; Receptor, Endothelin A; Risk Factors; Surveys and Questionnaires; Triglycerides; Waist Circumference

Intradialytic hypertension may be caused by an impaired endothelial cell response to hemodialysis. Carvedilol has been shown to improve endothelial cell function in vivo and to block endothelin-1 release in vitro. This study hypothesized that carvedilol would improve endothelial cell function and reduce the occurrence of intradialytic hypertension.. A prospective 12-week pilot study of carvedilol titrated to 50 mg twice daily was performed among 25 hemodialysis participants with intradialytic hypertension. Each patient served as his or her own control. Paired tests were used to analyze changes in BP and endothelial cell function--assessed by flow-mediated vasodilation, endothelial progenitor cells (aldehyde dehydrogenase bright activity and CD34(+)CD133(+)), asymmetric dimethylarginine, and endothelin-1--from baseline to study end.. Flow-mediated vasodilation was significantly improved with carvedilol (from 1.03% to 1.40%, P=0.02). There was no significant change in endothelial progenitor cells, endothelin-1, or asymmetric dimethylarginine. Although prehemodialysis systolic BP was unchanged (144-146 mmHg, P=0.5), posthemodialysis systolic BP, 44-hour ambulatory systolic BP, and the frequency of intradialytic hypertension decreased with carvedilol (159-142 mmHg, P<0.001; 155-148 mmHg, P=0.05; and 77% [4.6 of 6] to 28% [1.7 of 6], P<0.001, respectively).. Among hemodialysis participants with intradialytic hypertension, targeting endothelial cell dysfunction with carvedilol was associated with modest improvements in endothelial function, improved intradialytic and interdialytic BP, and reduced frequency of intradialytic hypertension. Randomized controlled trials are required to confirm these findings.

Topics: AC133 Antigen; Adult; Aged; Aldehyde Dehydrogenase; Antigens, CD; Antigens, CD34; Antihypertensive Agents; Arginine; Biomarkers; Blood Pressure; Blood Pressure Monitoring, Ambulatory; Body Weight; Carbazoles; Carvedilol; Endothelin-1; Endothelium, Vascular; Female; Glycoproteins; Humans; Hypertension; Male; Middle Aged; Peptides; Pilot Projects; Propanolamines; Prospective Studies; Renal Dialysis; Stem Cells; Texas; Time Factors; Treatment Outcome; Vascular Stiffness; Vasodilation; Vasodilator Agents

To study the effect of exenatide on body composition and circulating cardiovascular risk biomarkers.. Metformin-treated patients with type 2 diabetes (N = 69) were randomized to exenatide or insulin glargine and treated for 1 year. Body composition was evaluated by dual-energy X-ray absorptiometry. Additionally, body weight, waist circumference, and cardiovascular biomarkers were measured.. Treatment with exenatide for 1 year significantly reduced body weight, waist circumference, and total body and trunkal fat mass by 6, 5, 11, and 13%, respectively. In addition, exenatide increased total adiponectin by 12% and reduced high-sensitivity C-reactive protein by 61%. Insulin glargine significantly reduced endothelin-1 by 7%. These changes were statistically independent of the change in total body fat mass and body weight.. Exenatide treatment for 1 year reduced body fat mass and improved the profile of circulating biomarkers of cardiovascular risk. No significant changes were seen with insulin glargine except a trend for reduced endothelin-1 levels.

Topics: Absorptiometry, Photon; Adiponectin; Body Composition; Body Weight; C-Reactive Protein; Cardiovascular Diseases; Endothelin-1; Exenatide; Female; Humans; Hypoglycemic Agents; Insulin Glargine; Insulin, Long-Acting; Male; Middle Aged; Peptides; Risk Factors; Venoms; Waist Circumference

Habitual aerobic exercise results in a significant increase in central arterial compliance. Endothelin-1 (ET-1) is a potent endothelium-derived vasoconstrictor peptide and could play a role in mediating the habitual aerobic exercise-induced increase in central arterial compliance. The aim of the present study was to examine whether ET-1 is involved in the mechanisms underlying the increase in central arterial compliance with aerobic exercise training.. Seven apparently healthy middle-aged and older (60 +/- 3 years) adults underwent systemic endothelin-A/B (ET(A/B))-receptor blockade (500 mg of Tracleer) before and after 12 weeks of aerobic exercise training (70 +/- 1% of maximal heart rate, 44 +/- 2 min day(-1), 4.4 +/- 0.1 days week(-1)).. Basal carotid arterial compliance (via simultaneous B-mode ultrasound and arterial applanation tonometry on the common carotid artery) increased significantly after exercise training. Resting plasma ET-1 concentration decreased significantly after exercise training. Before exercise intervention, carotid arterial compliance increased significantly with the administration of the ET(A/B)-receptor blockade. After training, however, increases in carotid arterial compliance previously observed with the ET(A/B)-receptor blockade before training were abolished.. Regular aerobic exercise training enhances central arterial compliance in middle-aged and older humans. The increase in arterial compliance was associated with the corresponding reduction in plasma ET-1 concentration as well as the elimination of ET-1-mediated vascular tone. These results suggest that reductions in ET-1 may be an important mechanism underlying the beneficial effect of exercise training on central artery compliance.

Topics: Adipose Tissue; Aged; Antihypertensive Agents; Arteries; Blood Glucose; Blood Pressure; Body Weight; Bosentan; Carotid Arteries; Cholesterol; Compliance; Endothelin Receptor Antagonists; Endothelin-1; Exercise; Female; Heart Rate; Humans; Male; Middle Aged; Sulfonamides

To study the association between the indices of endothelial function in obstruction sleep apnea-hypopnea syndrome (OSAHS) and coronary heart disease (CHD) and the effect of nasal continuous positive airway pressure (nCPAP) on the combination of OSAHS and CHD.. A total of 80 subjects were prospectively recruited into four groups including control, OSAHS, CHD, OSAHS with CHD groups, with 20 subjects each. The indices of sleep apnea, serum nitric oxide (NO), and plasma endothelial-1 (ET-1) were measured. The changes of concentration of ET-1 and NO were compared before and after nCPAP therapy. The associations between ET-1 and NO and MSpO2, CT90 were analyzed.. (1) Multi-variable logistic analysis showed that OSAHS was one of the risk factors for CHD (OR = 0.511). (2) Compared with the control subjects and CHD group, there were significantly higher values of CT90, concentrations of ET-1 and lower values of MSpO2, concentrations of NO in both OSAHS and OSAHS with CHD groups (P < 0.01). There were no significant difference in sleep apnea indices between OSAHS and OSAHS with CHD groups (P > 0.05). However, in the group of OSAHS with CHD, the plasma ET-1 was significantly higher, whereas the serum NO was significantly lower than that in the group of OSAHS alone (P < 0.01). (3) The concentration of serum NO in the group of OSAHS was positively correlated with MSpO2 (r = 0.519, P < 0.05) and inversely correlated with CT90 (r = -0.529, P < 0.05). In addition, the concentration of plasma ET-1 was inversely correlated with MSpO2 (r = -0.457, P < 0.05) and positively correlated with CT90 (r = 0.476, P < 0.05). (4) In the groups of OSAHS and OSAHS with CHD, MSpO2, NO and NO/ET-1 after nCPAP therapy were higher than those before therapy, while CT90 and ET-1 were lower than those before therapy (P < 0.01).. OSAHS is one of the risk factors for CHD. Endothelial function was significantly impaired in OSAHS patients, and more severe in patients with OSAHS with CHD. The impairment of endothelial function may be one of the main mechanisms for the development or deterioration of CHD in OSAHS patients. The vascular endothelial dysfunction can be ameliorated by nCPAP treatment, which is correlated with improvement of nocturnal hypoxemia.

Topics: Adult; Body Weight; Continuous Positive Airway Pressure; Coronary Disease; Endothelin-1; Endothelium, Vascular; Female; Humans; Logistic Models; Male; Middle Aged; Nitric Oxide; Sleep Apnea, Obstructive

The occurrence of menopause is associated with an increased risk of cardiovascular events, and this has partly been attributed to the decline in circulating levels of estrogen. A lignan complex rich in the plant lignan secoisolariciresinol diglucoside (SDG) was isolated from flaxseed. SDG is metabolized by the colonic microflora to the mammalian lignans enterodiol and enterolactone and is hypothesized to be cardioprotective due to their structural similarity to estrogen. The aim of this study was to investigate the effect of a lignan complex, providing 500 mg/d of SDG, on markers of endothelial function. Healthy postmenopausal women (n = 22) completed a randomized, double-blind, placebo-controlled, crossover study. Women consumed daily a low-fat muffin, with or without a lignan complex, for 6 wk, separated by a 6-wk washout period. Flow-mediated, endothelium-dependent vasodilatation (FMD) and nitroglycerine-mediated, endothelium-independent vasodilatation were measured at the end of each intervention period. The sum of Plasma nitrite and nitrate (NOx), endothelin-1 (ET-1), and asymmetric dimethylarginine (ADMA) were measured at the beginning and end of each intervention period. FMD was 3.6 +/- 0.9% (mean +/- SEM) after the lignan complex intervention period compared with 3.9 +/- 0.7% after the placebo period (P = 0.72). Plasma concentrations of NOx, ET-1, and ADMA were not affected. We conclude that daily consumption for 6 wk of a low-fat muffin enriched with a lignan complex had no effect on endothelial function in healthy postmenopausal women.

Topics: 4-Butyrolactone; Aged; Arginine; Blood Pressure; Body Weight; Cross-Over Studies; Diet; Double-Blind Method; Endothelin-1; Endothelium, Vascular; Female; Flax; Humans; Lignans; Middle Aged; Nitrates; Nitrites; Nitroglycerin; Patient Compliance; Placebos; Postmenopause; Vasodilation

Endothelial dysfunction and inflammation are present in both type 2 diabetes mellitus (T2DM) and obesity. In this paper we compared the role of weight loss and of glycaemic control in determining circulating levels of ICAM-1, endothelin-1 (ET-1), and E-selectin in patients with morbid (grade 3) obesity.. ICAM-1, E-selectin, and ET-1 were higher in obese patients (n=96) than in lean controls (n=30); among obese patients, the three molecules were higher in T2DM patients (n=26) than in patients with normal (NGT, n=43) or impaired (IGT, n=27) glucose tolerance. Sixty-eight obese patients had a significant weight loss induced by bariatric surgery, and showed a significant decrease in blood glucose, HbA1c and all molecules, so that ICAM-1, E-selectin, and ET-1 were not different in NGT, IGT and T2DM patients, and in lean controls; in 13 patients with a small weight loss induced by diet, changes were not significant, in spite of a significant reduction in blood glucose and HbA1c. At stepwise regression, changes in ICAM-1, ET-1, and E-selectin significantly correlated only with change in body mass index.. These data indicate that weight loss is more important than glycaemic control in regulating circulating levels of ICAM-1, ET-1, E-selectin in morbidly obese subjects.

Topics: Adult; Blood Glucose; Body Weight; Diabetes Mellitus, Type 2; E-Selectin; Endothelin-1; Female; Follow-Up Studies; Glucose Intolerance; Glycated Hemoglobin; Humans; Insulin Resistance; Intercellular Adhesion Molecule-1; Male; Matched-Pair Analysis; Middle Aged; Obesity, Morbid; Reference Values; Regression Analysis; Weight Loss

Effects of hypobaric hypoxemia on endocrine and renal parameters of body fluid homeostasis were investigated in eight normal men during a sojourn of 8 days at an altitude of 4,559 m. Endocrine and renal responses to an osmotic stimulus (5% hypertonic saline, 3.6 ml/kg over 1 h) were investigated at sea level and on day 6 at altitude. Several days of hypobaric hypoxemia reduced body weight (-2.1 +/- 0.4 kg), increased plasma osmolality (+5.3 +/- 1.4 mosmol/kgH(2)O), elevated blood pressure (+12 +/- 1 mmHg), reduced creatinine clearance (122 +/- 6 to 96 +/- 10 ml/min), inhibited the renin system (19.5 +/- 2.0 to 10.9 +/- 0.9 mU/l) and plasma vasopressin (1.14 +/- 0.16 to 0.38 +/- 0.06 pg/ml), and doubled circulating levels of norepinephrine (103 +/- 16 to 191 +/- 35 pg/ml) and endothelin-1 (3.0 +/- 0.2 to 6.3 +/- 0.6 pg/ml), whereas urodilatin excretion rate decreased from day 2 (all changes P < 0.05 compared with sea level). Plasma arginine vasopressin response and the antidiuretic response to hypertonic saline loading were unchanged, but the natriuretic response was attenuated. In conclusion, chronic hypobaric hypoxemia 1) elevates the set point of plasma osmolality-to-plasma vasopressin relationship, possibly because of concurrent hypertension, thereby causing hypovolemia and hyperosmolality, and 2) blunts the natriuretic response to hypertonic volume expansion, possibly because of elevated circulating levels of norepinephrine and endothelin, reduced urodilatin synthesis, or attenuated inhibition of the renin system.

Topics: Adaptation, Physiological; Adult; Aldosterone; Altitude; Arginine Vasopressin; Atrial Natriuretic Factor; Blood Pressure; Body Weight; Creatinine; Endothelin-1; Epinephrine; Heart Rate; Humans; Hypertonic Solutions; Hypoxia; Infusions, Intravenous; Kidney; Kidney Function Tests; Male; Norepinephrine; Osmolar Concentration; Peptide Fragments; Renin; Sodium Chloride

The purpose of the study was to examine the relationship between the endothelin-1 (ET-1) concentration and the metabolic variables characteristic of the insulin resistance syndrome ([IRS] hyperinsulinemia, insulin resistance, hypertriglyceridemia, low high-density lipoprotein [HDL] cholesterol, visceral obesity, and glycemic abnormalities). The measurement of circulating ET-1 is a well-recognized marker of endothelial atherosclerotic and cardiovascular disease. Two hundred subjects were divided into 3 groups. Group 1 included 50 subjects with impaired glucose tolerance (IGT) or non-insulin-dependent diabetes mellitus (NIDDM) with IRS. Group 2 included 50 subjects with IGT or NIDDM without IRS. Group 3 included 100 normal subjects as controls. ET-1 levels were higher in group 1 versus groups 2 and 3 in women (11.2 +/- 0.7 v 7.9 +/- 0.5 and 6.6 +/- 0.4 pg/mL, P < .01) and men (10.1 +/- 0.6 v 6.5 +/- 0.8 and 7.2 +/- 0.3 pg/mL, P < .01). No differences were found between groups 2 and 3. With simple regression analysis, ET-1 levels significantly correlated with insulin, glycosylated hemoglobin, body weight, waist to hip ratio, and triglyceride values. However, with multiple regression analysis, only triglycerides (P < .009) and glycosylated hemoglobin (P < .001) remained independently correlated with ET-1. In conclusion, this cross-sectional study indicates that glycosylated hemoglobin and triglycerides are independently correlated with ET-1 levels in patients with IRS.

Topics: Blood Glucose; Body Weight; Cholesterol; Diabetes Mellitus, Type 2; Endothelin-1; Female; Glucose Tolerance Test; Glycated Hemoglobin; Humans; Insulin Resistance; Male; Middle Aged; Regression Analysis; Triglycerides

The mechanisms underlying the reduction in blood pressure that occurs with a severe energy-restricted diet were evaluated in 12 obese subjects during 8 days on a very-low-calorie diet (1.67 MJ/d) with a constant intake of 17 mmol sodium per day. The relationship between changes in blood pressure, sodium balance, plasma volume, renin-aldosterone and sympathetic nervous system activities, plasma C-terminus and N-terminus of the atrial natriuretic factor (ANF) prohormone, brain natriuretic peptide (BNP), and endothelin-1 (ET-1) concentrations was investigated. A negative sodium balance was present throughout the diet and was associated with a moderate reduction in plasma volume, a marked activation of the renin-aldosterone system, and a concomitant reduction in C- and N-terminal ANF prohormone levels. Moreover, the postural changes in N-terminal proANF and ANF secretion documented before the diet, disappeared after 8 days of dieting, in contrast to a greater postural stimulation of aldosterone and renin. A negative correlation was found between the changes of C- and N-terminal ANF prohormone levels and those of aldosterone. Urinary catecholamine excretion, BNP, and ET-1 remained unchanged. These results indicate that the decrease in blood pressure occurring during severe caloric restriction was essentially due to the reduction in the effective blood volume, as reflected by the stimulation of the renin-aldosterone system and the decrease in ANF levels. The lack of any changes in catecholamine excretion and endothelin levels suggests that peripheral vascular resistance did not change significantly in these circumstances.

Topics: Adolescent; Adult; Aldosterone; Atrial Natriuretic Factor; Blood Pressure; Blood Urea Nitrogen; Body Weight; Catecholamines; Creatinine; Data Interpretation, Statistical; Diet, Reducing; Electrolytes; Endothelin-1; Female; Food Deprivation; Heart Rate; Hormones; Humans; Hydrocortisone; Male; Middle Aged; Natriuretic Peptide, Brain; Nerve Tissue Proteins; Obesity; Plasma Volume; Renin; Sodium; Starvation; Uric Acid

Endothelin-1 (ET-1) is an endothelium-derived potent vasoconstrictor peptide that potentiates contractions to norepinephrine in human vessels. We previously reported that the circulating plasma concentration of ET-1 is significantly increased after exercise (S. Maeda, T. Miyauchi, K. Goto, and M. Matsuda. J. Appl. Physiol. 77: 1399-1402, 1994). To study the roles of ET-1 during and after exercise, we investigated whether endurance exercise affects the production of ET-1 in the circulation of working muscles and nonworking muscles. Male athletes performed one-leg cycle ergometer exercise of 30-min duration at intensity of 110% of their individual ventilatory threshold. Plasma concentrations of ET-1 in both sides of femoral veins (veins in the working leg and nonworking leg) and in the femoral artery (artery in the nonworking leg) were measured before and after exercise. The plasma ET-1 concentration in the femoral vein in the nonworking leg was significantly increased after exercise, whereas that in femoral vein in the working leg was not changed. The arteriovenous difference in ET-1 concentration was significantly increased after exercise in the circulation of the nonworking leg but not of the working leg, which suggests that the production of ET-1 was increased in the circulation of the nonworking leg by exercise. The present study also demonstrated that the plasma norepinephrine concentrations were elevated by exercise in the femoral veins of both the working and nonworking legs, suggesting that the sympathetic nerve activity was augmented in both legs during exercise. Therefore, the present study demonstrates the possibility that the increase in production of ET-1 in nonworking muscles may cause vasoconstriction and hence decrease blood flow in nonworking muscles through its direct vasoconstrictive action or through an indirect effect of ET-1 to enhance vasoconstrictions to norepinephrine and that these responses may be helpful in increasing blood flow in working muscles. We propose that endogenous ET-1 contributes to the exercise-induced redistribution of blood flow in muscles.

Topics: Adolescent; Adult; Blood Pressure; Body Weight; Endothelin-1; Exercise; Exercise Test; Hematocrit; Humans; Male; Muscle, Skeletal; Norepinephrine; Regional Blood Flow

Hyperthyroidism promotes the development and progression of cardiovascular diseases (CVD). Aldosterone, a key mediator of myocardial inflammation, oxidative stress and fibrosis, may be activated in hyperthyroidism.. To assess the impact of hyperthyroidism on aldosterone levels and myocardial oxidative status, inflammatory and fibrotic markers in hyperthyroid rats, and to test if the use of spironolactone (an aldosterone antagonist) attenuates these changes.. Adult Wistar rats were randomly distributed into 4 groups; controls, spironolactone treated rats (Spir, 50mg/kg/day), hyperthyroid rats (Hyper, daily intraperitoneal levothyroxine 0.3mg/kg/day), and spironolactone treated hyperthyroid rats (Hyper+Spir) for 4 weeks. Blood pressure (Bp), and levels of serum and myocardial aldosterone, oxidants/antioxidants, inflammatory and fibrotic markers were measured.. Levothyroxine increased serum thyroid hormones and increased Bp, heart rate and heart to bodyweight ratio. Relative to control, serum aldosterone levels were increased in Hyper and Hyper+ Spir groups. In parallel, cardiac lipid peroxides and serum endothelin-1 were increased whereas cardiac superoxide dismutase, catalase, glutathione, and matrix metalloproteinase -2 were reduced in the Hyper group. Spironolactone decreased serum thyroid hormones and improved cardiac lipid peroxides and metalloproteinase -2 levels. The use of spironolactone decreased serum nitrite levels and increased cardiac SOD and glutathione. Cardiac levels of aldosterone, endothelin-1, transforming growth factor-beta and nitrite were similar among all groups.. Hyperthyroid status was associated with an increase in aldosterone and oxidant/ inflammatory biomarkers. The use of spironolactone enhanced antioxidant defenses. Aldosterone antagonists may serve as potential drugs to attenuate the development of cardiac disease in hyperthyroidism.

Topics: Aldosterone; Animals; Antioxidants; Biomarkers; Blood Pressure; Body Weight; Cardiovascular Diseases; Endothelin-1; Heart; Heart Rate; Hyperthyroidism; Male; Mineralocorticoid Receptor Antagonists; Myocardium; Nitrites; Organ Size; Oxidative Stress; Random Allocation; Rats; Spironolactone; Thyroid Hormones; Thyroxine; Transforming Growth Factor beta

High salt intake (HS) is associated with obesity and insulin resistance. ET-1, a peptide released in response to HS, inhibits the actions of insulin on cultured adipocytes through ET-1 type B (ETB) receptors; however, the in vivo implications of ETB receptor activation on lipid metabolism and insulin resistance is unknown. We hypothesized that activation of ETB receptors in response to HS intake promotes dyslipidemia and insulin resistance. In normal salt (NS) fed rats, no significant difference in body mass or epididymal fat mass was observed between control and ETB deficient rats. After 2 weeks of HS, ETB-deficient rats had significantly lower body mass and epididymal fat mass compared to controls. Nonfasting plasma glucose was not different between genotypes; however, plasma insulin concentration was significantly lower in ETB-deficient rats compared to controls, suggesting improved insulin sensitivity. In addition, ETB-deficient rats had higher circulating free fatty acids in both NS and HS groups, with no difference in plasma triglycerides between genotypes. In a separate experiment, ETB-deficient rats had significantly lower fasting blood glucose and improved glucose and insulin tolerance compared to controls. These data suggest that ET-1 promotes adipose deposition and insulin resistance via the ETB receptor.

Topics: Adipose Tissue; Adiposity; Animals; Blood Glucose; Body Weight; Disease Models, Animal; Dyslipidemias; Endothelin-1; Fatty Acids, Nonesterified; Humans; Insulin; Insulin Resistance; Male; Mutation; Rats; Rats, Transgenic; Receptor, Endothelin B; Sodium Chloride, Dietary

BackgroundThe pathogenesis of idiopathic nephrotic syndrome (INS) remains unclear, although recent studies suggest endothelin 1 (ET-1) and CD80 of podocytes are involved. We investigated the potential of antagonist to ET-1 receptor type A (ETRA) as therapeutic agent through the suppression of CD80 in a rat model of INS.MethodsPuromycin aminonucleoside (PAN) was injected to Wister rats to induce proteinuria: some were treated with ETRA antagonist and others were treated with 0.5% methylcellulose. Blood and tissue samples were collected. Quantitative PCR was used to determine the expression of Toll-like receptor-3 (TLR-3), nuclear factor-κB (NF-κB), CD80, talin, ETRA, and ET-1 in the kidney. To confirm the level of CD80 protein expression, immunofluorescence staining and western blot analysis of the renal tissue were performed.ResultsAmount of proteinuria in the treatment group was significantly lower than the other groups. The same-day body weight, serum creatinine values, and blood pressure were not significantly different. ETRA antagonist restores podocyte foot process effacement as well as the aberrant expression of TLR-3, nuclear factor-κB (NF-κB), and CD80 in PAN-injured kidneys.ConclusionsThe ETRA antagonist may be promising drug for INS as it showed an antiproteinuric effect. Its action was considered to be through suppression of CD80 expression on podocytes.

Topics: Animals; B7-1 Antigen; Blood Pressure; Body Weight; Creatinine; Disease Models, Animal; Endothelin A Receptor Antagonists; Endothelin-1; Female; Kidney; Kidney Diseases; Kidney Glomerulus; Nephrosis; Nephrotic Syndrome; NF-kappa B; Phenylpropionates; Podocytes; Proteinuria; Puromycin Aminonucleoside; Pyridazines; Rats; Rats, Wistar; Receptor, Endothelin A; Toll-Like Receptor 3

The aim of this study was to investigate the regulatory mechanism of endothelin-1 (ET-1), an endothelium-derived vasoconstrictor, on adipogenesis in vitro and in vivo.. 3T3-L1 preadipocytes were used to explore the mechanisms mediating ET-1 actions on preadipocyte proliferation and adipocyte differentiation. To investigate the in vivo effect of ET-1, male Sprague-Dawley rats were infused with ET-1 or saline for 4 weeks via intraperitoneally implanted osmotic pumps, and the fat pad weight and adipocyte size of adipose tissues were measured.. ET-1 stimulated preadipocyte proliferation and increased the cell number at the mitotic clonal expansion stage of adipocyte differentiation via the endothelin A receptor (ETAR) and activation of the protein kinase C (PKC) pathway. ET-1, via ETAR, inhibited adipocyte differentiation partially through an ERK-dependent pathway. Furthermore, no significant difference in the body weight and fat pad weight was observed in either ET-1- or saline-infused rats. Compared with saline-infused rats, the adipocyte cell number was significantly increased but the adipocyte size was significantly decreased in ET-1-infused rats.. Chronic ET-1 infusion increased the number of small adipocytes without the change of white adipose tissue mass in rats, which were associated with ET-1-stimulated preadipocyte proliferation, but not ET-1-suppressed adipocyte differentiation.

Topics: 3T3-L1 Cells; Adipocytes; Adipogenesis; Adipose Tissue; Animals; Body Weight; Cell Differentiation; Dose-Response Relationship, Drug; Endothelin-1; Hyperplasia; Male; Mice; Obesity; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A

Pulmonary arterial hypertension (PAH) progressively leads to increases in pulmonary vasoconstriction. Modafinil plays a role in vasorelaxation and blocking KCa3.1 channel with a result of elevating intracellular cyclic adenosine monophosphate (cAMP) levels. The purpose of this study is to evaluate the effects on modafinil in monocrotaline (MCT)-induced PAH rat.. The rats were separated into three groups: the control group, the monocrotaline (M) group (MCT 60 mg/kg), and the modafinil (MD) group (MCT 60 mg/kg + modafinil).. Reduced right ventricular pressure (RVP) was observed in the MD group. Right ventricular hypertrophy was improved in the MD group. Reduced number of intra-acinar pulmonary arteries and medial wall thickness were noted in the MD group. After the administration of modafinil, protein expressions of endothelin-1 (ET-1), endothelin receptor A (ERA) and KCa3.1 channel were significantly reduced. Modafinil suppressed pulmonary artery smooth muscle cell (PASMC) proliferation via cAMP and KCa3.1 channel. Additionally, we confirmed protein expressions such as Bcl-2-associated X, vascular endothelial growth factor, tumor necrosis factor-α, and interleukin-6 were reduced in the MD group.. Modafinil improved PAH by vasorelaxation and a decrease in medial thickening via ET-1, ERA, and KCa3.1 down regulation. This is a meaningful study of a modafinil in PAH model.

Topics: Animals; Benzhydryl Compounds; Body Weight; Cyclic AMP; Disease Models, Animal; Endothelin-1; Gene Expression Regulation; Heart Ventricles; Humans; Hypertension, Pulmonary; Intermediate-Conductance Calcium-Activated Potassium Channels; Male; Modafinil; Monocrotaline; Myocytes, Smooth Muscle; Pressure; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Vasoconstriction

The involvement of choline and its metabolite trimethylamine-N-oxide (TMAO) in endothelial dysfunction and atherosclerosis has been repeatedly confirmed. Phloretin, a dihydrochalcone flavonoid usually present in apples, possesses a variety of biological activities including vascular nutrition. This study was designed to investigate whether phloretin could alleviate or prevent high choline-induced vascular endothelial dysfunction and liver injury in mice. Mice were provided with 3% high choline water and given phloretin orally daily for 10 weeks. The high choline-treated mice showed the significant dyslipidemia and hyperglycemia with the impaired liver and vascular endothelium (p < 0.01). Administration of phloretin at 200 and 400 mg/kg bw significantly reduced the choline-induced elevation of serum TC, TG, LDL-C, AST, ALT, ET-1 and TXA2 (p < 0.01), and markedly antagonized the choline-induced decrease of serum PGI2, HDL-C and NO levels. Furthermore, phloretin elevated hepatic SOD and GSH-Px activities and decreased hepatic MDA levels of the mice exposed to high choline water. Moreover, histopathological test with the H&E and Oil Red O staining of liver sections confirmed the high choline diet-caused liver steatosis and the hepatoprotective effect of phloretin. These findings suggest that high choline causes oxidative damage, and phloretin alleviate vascular endothelial dysfunction and liver injury.

Topics: Alanine Transaminase; Animals; Aspartate Aminotransferases; Body Weight; Choline; Diet; Endothelin-1; Endothelium, Vascular; Epoprostenol; Fatty Acids, Nonesterified; Lipids; Liver; Male; Malondialdehyde; Mice; Nitric Oxide; Phloretin

Metabolic syndrome including obesity, dyslipidemia and hypertension is a cluster of risk factors of cardiovascular disease. Fermentation of medicinal herbs improves their pharmacological efficacy. Red ginseng (RG), a widely used traditional herbal medicine, was reported with anti-inflammatory and anti-oxidant activity. Aim in the present study was to investigate that the effects of fermented red ginseng (FRG) on a high-fructose (HF) diet induced metabolic disorders, and those effects were compared to RG and losartan. Animals were divided into four groups: a control group fed a regular diet and tap water, and fructose groups that were fed a 60% high-fructose (HF) diet with/without RG 250 mg/kg/day or FRG 250 mg/kg/day for eight weeks, respectively. Treatment with FRG significantly suppressed the increments of body weight, liver weight, epididymal fat weight and adipocyte size. Moreover, FRG significantly prevented the development of metabolic disturbances such as hyperlipidemia and hypertension. Staining with Oil-red-o demonstrated a marked increase of hepatic accumulation of triglycerides, and this increase was prevented by FRG. FRG ameliorated endothelial dysfunction by downregulation of endothelin-1 (ET-1) and adhesion molecules in the aorta. In addition, FRG induced markedly upregulation of Insulin receptor substrate 1 (IRS-1) and glucose transporter type 4 (Glut4) in the muscle. These results indicate that FRG ameliorates obesity, dyslipidemia, hypertension and fatty liver in HF diet rats. More favorable pharmacological effects on HF diet induced metabolic disorders were observed with FRG, compared to an equal dose of RG. These results showed that the pharmacological activity of RG was enhanced by fermentation. Taken together, fermentated red ginseng might be a beneficial therapeutic approach for metabolic syndrome.

Topics: Adipocytes; Alanine Transaminase; Animals; Aspartate Aminotransferases; Blood Glucose; Blood Pressure; Body Weight; Cholesterol, HDL; Cholesterol, LDL; Disease Models, Animal; Down-Regulation; Endothelin-1; Fermentation; Fructose; Glucose Transporter Type 4; Insulin Receptor Substrate Proteins; Liver; Losartan; Metabolic Syndrome; Obesity; Organ Size; Panax; Phytotherapy; Plant Preparations; Rats; Triglycerides; Up-Regulation

The differences in endothelial function between Tibetan and Han nationality population have not been fully investigated. The aim of this work is to investigate the differences in endothelial function and plasma endothelin 1 (ET-1) concentration between Tibetan and Han male population.. Totally 272 Tibetan male subjects aged 42.9 ± 9.4 years were enrolled in this study to stand for Tibetan population. All of them were native residents in Lhasa City. And 580 Qinghai-Tibet Railway constructors with Han nationality aged 41.8 ± 11.1 years were enrolled in this study to stand for Han nationality population. All of them were male subjects and lived in Lhasa City for at least 1 year. All subjects lived in the same high-altitude area (the altitude of Lhasa is 3658 m). Height, weight, waist circumference, hip circumference, systolic blood pressure, diastolic blood pressure were evaluated. Body mass index (BMI) was calculated. Brachial artery flow-mediated dilation (FMD) was measured in the fasting state using high-resolution B-mode ultrasound. Computer-assisted analysis software was used to calculate brachial artery diameters. Venous blood was sampled for the measurement of total cholesterol (CH), triglyceride (TG), high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL) and HbA1c. Plasma ET-1 was quantitated using a commercially available ELISA kits.. Totally 272 Tibetan subjects and 580 Han nationality subjects were enrolled in this study. BMI and waist-hip ratio in Tibetan subjects were much higher than those in Han subjects (p < 0.01). LDL cholesterol level and plasma ET-1 concentration in Tibetan subjects were significantly higher than Han subjects (p < 0.01). The baseline brachial artery diameter in Tibetan group was much higher than that of Han group (p < 0.01). The absolute and percent changes in brachial artery diameter were lower in Tibetan population compared with Han population (p < 0.01). The linear regression analysis showed that LDL cholesterol, and plasma ET-1 were correlated with FMD (p < 0.01).. Endothelial function and plasma ET-1 concentration were different between Tibetan and Han male populations.

Topics: Body Weight; China; Cholesterol; Endothelin-1; Endothelium, Vascular; Ethnicity; Humans; Male; Tibet; Triglycerides; Waist Circumference

To explore the mechanisms underlying endothelin-1 (ET-1) elevations induced by excessive fluoride exposure.. We measured serum and bone fluoride ion content and plasma ET-1 levels and compared these parameters among different groups in an animal model. We also observed morphological changes in the aorta and endothelium of rabbits. In cell experiments, human umbilical vein endothelial cells (HUVECs) were treated with varying concentrations of NaF for 24h, with or without 10 µM U0126 pretreatment for 1 h. ET-1 levels in culture fluid and intracellular reactive oxygen species (ROS) levels, as well as ET1 gene, endothelin-converting enzyme-1 (ECE-1), extracellular signal-regulating kinase 1/2 (ERK1/2), pERK1/2 expression levels and RAS activation were measured and compared among the groups.. Plasma ET-1 levels of rabbits increased significantly in fluorinated groups compared with those in the control group. The rabbit thoracic aortas became slightly hardened in fluorinated groups compared with those in the control group, and some vacuoles were present in the endothelial cell cytoplasm of the rabbits in fluorinated groups. In our cell experiments, ET1 gene and ECE-1 expression levels in HUVECs and ET-1 expression levels in the cell culture supernatants increased significantly in some experimental groups compared with those in the control group. These trends paralleled the changes in intracellular ROS levels, RAS activation, and the pERK1/2-to-ERK1/2 ratio. After U0126 was added, ECE-1 expression and ET-1 levels decreased significantly.. Excessive fluoride exposure leads to characteristic endothelial damage (vacuoles), thoracic aorta hardening, and plasma ET-1 level elevations in rabbits. In addition, the ROS-RAS-MEK1/2-pERK1/2/ERK1/2 pathway plays a crucial-and at least partial-role in ET-1 over-expression, which is promoted by excessive fluoride exposure.

Topics: Animals; Aorta; Body Weight; Butadienes; Cell Proliferation; Diet; Drinking Water; Endothelin-1; Endothelin-Converting Enzymes; Endothelium, Vascular; Extracellular Signal-Regulated MAP Kinases; Fluorides; Gene Expression Regulation; Human Umbilical Vein Endothelial Cells; Intracellular Space; Ions; Male; Nitriles; Phosphorylation; Rabbits; ras Proteins; Reactive Oxygen Species; Vacuoles

Stroke is the third leading cause of death and permanent disability in the United States, often producing long-term cognitive impairments, which are not easily recapitulated in animal models. The goals of this study were to assess whether: (1) the endothelin-1 (ET-1) model of chronic stroke produced discernable cognitive deficits; (2) a spatial operant reversal task (SORT) would accurately measure memory deficits in this model; and (3) bone-marrow-derived mesenchymal stem cells (BMMSCs) could reduce any observed deficits.. Rats were given unilateral intracerebral injections of vehicle or ET-1, a stroke-inducing agent, near the middle cerebral artery. Seven days later, they were given intrastriatal injections of BMMSCs or vehicle, near the ischemic penumbra. The cognitive abilities of the rats were assessed on a novel SORT, which was designed to efficiently distinguish cognitive deficits from potential motoric confounds.. Rats given ET-1 had significantly more cognitive errors at six weeks post-stroke on the SORT, and that these deficits were attenuated by BMMSC transplants.. These findings indicate that: (1) the ET-1 model produces chronic cognitive deficits; (2) the SORT efficiently measures cognitive deficits that are not confounded by motoric impairment; and (3) BMMSCs may be a viable treatment for stroke-induced cognitive dysfunction.

Topics: Animals; Body Weight; Brain; Chronic Disease; Cognition Disorders; Conditioning, Operant; Disease Models, Animal; Endothelin-1; Female; Male; Mesenchymal Stem Cell Transplantation; Psychological Tests; Rats, Sprague-Dawley; Stroke; Treatment Outcome

Nesfatin is a peptide secreted by peripheral tissues, central and peripheral nervous system. It is involved in the regulation of homeostasis. Although the effects of nesfatin-1 on nutrition have been studied widely in the literature, the mechanisms of nesfatin-1 action and also relations with other physiological parameters are still not clarified well. We aimed to investigate the effect of peripheral chronic nesfatin-1 application on blood pressure regulation in normal and in rats exposed to restraint immobilization stress. In our study, three month-old male Wistar rats were used. Rats were divided into 4 groups as Control, Stress, Control+Nesfatin-1, Nesfatin-1+Stress. Angiotensinogen, angiotensin converting enzyme 2, angiotensin II, endothelin-1, endothelial nitric oxide synthase, aldosterone, cortisol, nesfatin-1 levels were determined in plasma samples by ELISA. Our results have shown that chronic peripheral nesfatin-1 administration increases blood pressure in normal and in rats exposed to chronic restraint stress. Effect of nesfatin-1 on circulating level of angiotensinogen, angiotensin converting enzyme 2, angiotensin II, endothelin-1, endothelial nitric oxide synthase, aldosterone and cortisol has been identified. We can conclude that elevated high blood pressure after chronic peripheral nesfatin-1 administration in rats exposed to chronic restraint stress may be related to decreased plasma level of endothelial nitric oxide synthase concentration.

Topics: Animals; Blood Pressure; Body Weight; Calcium-Binding Proteins; DNA-Binding Proteins; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Gene Expression Regulation, Enzymologic; Male; Nerve Tissue Proteins; Nitric Oxide Synthase Type III; Nucleobindins; Rats; Rats, Wistar; Renin-Angiotensin System; Stress, Physiological

In the developing heart, cardiomyocytes undergo terminal differentiation during a critical window around birth. Hypoxia is a major stress to preterm infants, yet its effect on the development and maturation of the heart remains unknown. We tested the hypothesis in a rat model that newborn anoxia accelerates cardiomyocyte terminal differentiation and results in reduced cardiomyocyte endowment in the developing heart via an endothelin-1-dependent mechanism. Newborn rats were exposed to anoxia twice daily from postnatal day 1 to 3, and hearts were isolated and studied at postnatal day 4 (P4), 7 (P7), and 14 (P14). Anoxia significantly increased HIF-1α protein expression and pre-proET-1 mRNA abundance in P4 neonatal hearts. Cardiomyocyte proliferation was significantly decreased by anoxia in P4 and P7, resulting in a significant reduction of cardiomyocyte number per heart weight in the P14 neonates. Furthermore, the expression of cyclin D2 was significantly decreased due to anoxia, while p27 expression was increased. Anoxia has no significant effect on cardiomyocyte binucleation or myocyte size. Consistently, prenatal hypoxia significantly decreased cardiomyocyte proliferation but had no effect on binucleation in the fetal heart. Newborn administration of PD156707, an ETA-receptor antagonist, significantly increased cardiomyocyte proliferation at P4 and cell size at P7, resulting in an increase in the heart to body weight ratio in P7 neonates. In addition, PD156707 abrogated the anoxia-mediated effects. The results suggest that hypoxia and anoxia via activation of endothelin-1 at the critical window of heart development inhibits cardiomyocyte proliferation and decreases myocyte endowment in the developing heart, which may negatively impact cardiac function later in life.

Topics: Animals; Animals, Newborn; Body Weight; Cell Count; Cell Hypoxia; Cell Proliferation; Cell Size; Dioxoles; Endothelin A Receptor Antagonists; Endothelin-1; Female; Fetal Heart; Gene Expression Regulation; Hypoxia-Inducible Factor 1, alpha Subunit; Myocytes, Cardiac; Organ Size; Pregnancy; Proliferating Cell Nuclear Antigen; Protein Precursors; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; RNA, Messenger

Decabrominated diphenyl ether (PBDE-209) is a persistent organic pollutant. Gestational exposure to PBDE-209 can accumulate in pregnant women and fetuses via the placenta and umbilical cord, affecting perinatal outcome. In this study, pregnant Sprague-Dawley (SD) rats were randomly divided into five groups and intragastrically administered peanut oil (vehicle) 1, 5 and 10mg/kg by body weight (b.w.) of PBDE-209, or nothing (control) from day 0 (G0) to day 21 (G21) gestation, respectively. Placental samples were collected on G21 by cesarean section. The mRNA and protein expressions of ET-1, eNOS and iNOS in the placenta were examined using qRT-PCR and Western blot, respectively. Total nitric oxide (NO) in the placenta was measured using a specific ELISA kit. Compared with the control and vehicle groups, the mRNA expression of ET-1 and iNOS in the placenta was gradually and significantly increased after exposure to increasing concentrations of PBDE-209 (P<0.05), while the mRNA level of eNOS in the placenta was gradually and significantly reduced after exposure to increasing concentrations of PBDE-209 (P<0.05). The expression trends of ET-1, eNOS and iNOS proteins were consistent with those of mRNA expression. Interestingly, the production of total NO was significantly increased after exposure to 5 and 10mg/kg b.w. PBDE-209 (P<0.05). Finally, the birth weight of the offspring rats was significantly reduced after maternal exposure to 5 and 10 mg/kg b.w. PBDE-209 compared with the control and vehicle groups (P<0.05). These results suggest that PBDE-209 exposure during pregnancy upregulates ET-1 and iNOS expression, but decreases eNOS expression in the placenta, as well as reduces the birth weight of offspring.

Topics: Analysis of Variance; Animals; Body Weight; Dose-Response Relationship, Drug; Endothelin-1; Female; Gene Expression Regulation, Developmental; Halogenated Diphenyl Ethers; Male; Nitric Oxide Synthase Type III; Placenta; Pregnancy; Prenatal Exposure Delayed Effects; Rats; Rats, Sprague-Dawley; RNA, Messenger

Neprilysin inhibitors prevent the breakdown of bradykinin and natriuretic peptides, promoting vasodilation and natriuresis. However, they also increase angiotensin II and endothelin-1. Here we studied the effects of a low and a high dose of the neprilysin inhibitor thiorphan on top of AT1 receptor blockade with irbesartan versus vehicle in TGR(mREN2)27 rats with high renin hypertension. Mean arterial blood pressure was unaffected by vehicle or thiorphan alone. Irbesartan lowered blood pressure, but after 7 days pressure started to increase again. Low- but not high-dose thiorphan prevented this rise. Only during exposure to low-dose thiorphan plus irbesartan did heart weight/body weight ratio, cardiac atrial natriuretic peptide expression, and myocyte size decrease significantly. Circulating endothelin-1 was not affected by low-dose thiorphan with or without irbesartan, but increased after treatment with high-dose thiorphan plus irbesartan. This endothelin-1 rise was accompanied by an increase in renal sodium-hydrogen exchanger 3 protein abundance, and an upregulation of constrictor vascular endothelin type B receptors. Consequently, the endothelin type B receptor antagonist BQ788 no longer enhanced endothelin-1-induced vasoconstriction (indicative of endothelin type B receptor-mediated vasodilation), but prevented it. Thus, optimal neprilysin inhibitor dosing reveals additional cardioprotective effects on top of AT1 receptor blockade in renin-dependent hypertension.

Topics: Angiotensin II Type 1 Receptor Blockers; Animals; Arterial Pressure; Atrial Natriuretic Factor; Biphenyl Compounds; Body Weight; Endothelin B Receptor Antagonists; Endothelin-1; Irbesartan; Kidney; Myocardium; Myocytes, Cardiac; Neprilysin; Oligopeptides; Organ Size; Piperidines; Protease Inhibitors; Rats; Receptor, Angiotensin, Type 1; Receptor, Endothelin B; Renin-Angiotensin System; Sodium-Hydrogen Exchanger 3; Sodium-Hydrogen Exchangers; Tetrazoles; Thiorphan; Up-Regulation; Vasoconstriction; Vasodilation

Vascular endothelial dysfunction and inflammatory response are early events during initiation and progression of atherosclerosis. In vitro studies have described that CIT markedly upregulates expressions of ICAM-1 and VCAM-1 of endothelial cells, which result from NF-κB activation induced by CIT. In order to determine whether it plays a role in atherogenesis in vivo, we conducted the study to investigate the effects of CIT on atherosclerotic plaque development and inflammatory response in apolipoprotein E deficient (apoE-/-) mice. Five-week-old apoE-/- mice were fed high-fat diets and treated with CIT for 15 weeks, followed by assay of atherosclerotic lesions. Nitric oxide (NO), vascular endothelial growth factor (VEGF) and endothelin-1 (ET-1) were detected in serum. Levels of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), VEGF, and ET-1 in plaque areas of artery walls were examined. NF-κB p65 expression and NF-κB activation in aorta also were assessed. CIT treatment significantly augmented atherosclerotic plaques and increased expressions of ICAM-1, VCAM-1, VEGF and ET-1 in aorta. Mechanistic studies showed that activation of NF-κB was significantly elevated by CIT treatment, indicating the effect of CIT on atherosclerosis may be regulated by activation of NF-κB.

Topics: Animals; Aorta; Apolipoproteins E; Atherosclerosis; Aurovertins; Body Weight; Diet, High-Fat; Endothelin-1; Endothelium, Vascular; Hypercholesterolemia; Inflammation; Intercellular Adhesion Molecule-1; Lipids; Male; Mice, Inbred C57BL; NF-kappa B; Nitric Oxide; Up-Regulation; Vascular Cell Adhesion Molecule-1; Vascular Endothelial Growth Factor A

Millions of Mexico, US and across the world children are overweight and obese. Exposure to fossil-fuel combustion sources increases the risk for obesity and diabetes, while long-term exposure to fine particulate matter (PM2.5) and ozone (O3) above US EPA standards is associated with increased risk of Alzheimer's disease (AD). Mexico City Metropolitan Area children are chronically exposed to PM2.5 and O3 concentrations above the standards and exhibit systemic, brain and intrathecal inflammation, cognitive deficits, and Alzheimer disease neuropathology. We investigated adipokines, food reward hormones, endothelial dysfunction, vitamin D and apolipoprotein E (APOE) relationships in 80 healthy, normal weight 11.1±3.2 year olds matched by age, gender, BMI and SES, low (n: 26) versus high (n:54) PM2.5 exposures. Mexico City children had higher leptin and endothelin-1 (p<0.01 and p<0.000), and decreases in glucagon-like peptide-1 (GLP 1), ghrelin, and glucagon (<0.02) versus controls. BMI and leptin relationships were significantly different in low versus high PM2.5 exposed children. Mexico City APOE 4 versus 3 children had higher glucose (p=0.009). Serum 25-hydroxyvitamin D<30 ng/mL was documented in 87% of Mexico City children. Leptin is strongly positively associated to PM 2.5 cumulative exposures. Residing in a high PM2.5 and O3 environment is associated with 12h fasting hyperleptinemia, altered appetite-regulating peptides, vitamin D deficiency, and increases in ET-1 in clinically healthy children. These changes could signal the future trajectory of urban children towards the development of insulin resistance, obesity, type II diabetes, premature cardiovascular disease, addiction-like behavior, cognitive impairment and Alzheimer's disease. Increased efforts should be made to decrease pediatric PM2.5 exposures, to deliver health interventions prior to the development of obesity and to identify and mitigate environmental factors influencing obesity and Alzheimer disease.

Topics: Adolescent; Alzheimer Disease; Body Weight; Case-Control Studies; Child; Cohort Studies; Endothelin-1; Hormones; Humans; Leptin; Mexico; Obesity; Particulate Matter; Vitamin D Deficiency

Severe pulmonary arterial hypertension (PAH) is an incurable disease whose exact mechanisms remain unknown. However, growing evidence highlights the role of inflammation and endothelin (ET) signaling. The lack of reliable models makes it difficult to investigate the pathophysiology of this disease. Our aim was therefore to develop a mouse model of severe PAH closely mimicking the human condition to explore the role of interleukin-6 (IL-6), and ET signaling in advanced PAH progression.. Young male SV129 mice received vascular endothelial growth factor receptor inhibitor (SU5416) three times a week and were exposed to hypoxia (10% O2) for three weeks. Molecular analysis and histological assessment were examined using real-time PCR, Western blot and immunostaining, respectively.. The developed murine model presented important characteristics of severe PAH in human: concentric neointimal wall thickening, plexogenic lesions, recruitment of macrophages, and distal arteriolar wall muscularization. We detected an increase of IL-6 production and a stronger macrophage recruitment in adventitia of remodeled arterioles developing plexogenic lesions. Moreover, ET-1 and ET receptor A were up-regulated in lung lysates and media of remodeled arterioles. Recombinant IL-6 stimulated the proliferation and regulated endothelial cells in increasing ET-1 and decreasing ET receptor B.. These data describe a murine model, which displays the most important features of human severe PAH. We assume that inflammation, particularly IL-6 regulating ET signaling, plays a crucial role in forming plexogenic lesions. This model is thus reliable and might be used for a better understanding of severe PAH progression and treatment.

Topics: Animals; Biomarkers; Body Weight; Cell Hypoxia; Cell Line; Disease Models, Animal; Endothelial Cells; Endothelin-1; Heart Rate; Humans; Hypertension, Pulmonary; Indoles; Inflammation; Interleukin-6; Lung; Male; Mice; Pulmonary Artery; Pyrroles; Receptors, Vascular Endothelial Growth Factor; Signal Transduction; Up-Regulation

The effects of simulated heat waves on body weight, body temperature, and biomarkers of cardiac function in ApoE-/- mice were investigated. Heat waves were simulated in a meteorological environment simulation chamber according to data from a heat wave that occurred in July 2001 in Nanjing, China. Eighteen ApoE-/- mice were divided into control group, heat wave group, and heat wave BH4 group. Mice in the heat wave and BH4 groups were exposed to simulated heat waves in the simulation chamber. Mice in BH4 group were treated with gastric lavage with BH4 2 h prior to heat wave exposure. Results showed that the heat waves did not significantly affect body weight or ET-1 levels. However, mice in the heat wave group had significantly higher rectal temperature and NO level and lower SOD activity compared with mice in the control group (p < 0.01), indicating that heat wave had negative effects on cardiac function in ApoE-/- mice. Gastric lavage with BH4 prior to heat wave exposure significantly reduced heat wave-induced increases in rectal temperature and decreases in SOD activity. Additionally, pretreatment with BH4 further increased NO level in plasma. Collectively, these beneficial effects demonstrate that BH4 may potentially mitigate the risk of coronary heart disease in mice under heat wave exposure. These results may be useful when studying the effects of heat waves on humans.

Topics: Animals; Atherosclerosis; Biomarkers; Biopterins; Body Temperature; Body Weight; Coronary Disease; Drug Evaluation, Preclinical; Endothelin-1; Extreme Heat; Infrared Rays; Male; Mice; Mice, Knockout; Nitric Oxide; Random Allocation; Superoxide Dismutase

This study investigates whether endothelin-1 (ET-1) mediates monocrotaline (MCT)-induced pulmonary artery hypertension (PAH) and right ventricular hypertrophy (RVH), and if so, whether the G-protein coupled receptor antagonist KMUP-1 (7-{2-[4-(2-chlorobenzene)piperazinyl]ethyl}-1,3-dimethylxanthine) inhibits ET-1-mediated PA constriction and the aforementioned pathological changes. In a chronic rat model, intraperitoneal MCT (60 mg/kg) induced PAH and increased PA medial wall thickening and RV/left ventricle + septum weight ratio on Day 21 after MCT injection. Treatment with sublingual KMUP-1 (2.5 mg/kg/day) for 21 days prevented these changes and restored vascular endothelial nitric oxide synthase (eNOS) immunohistochemical staining of lung tissues. Western blotting analysis demonstrated that KMUP-1 enhanced eNOS, soluble guanylate cyclase, and protein kinase G levels, and reduced ET-1 expression and inactivated Rho kinase II (ROCKII) in MCT-treated lung tissue over long-term administration. In MCT-treated rats, KMUP-1 decreased plasma ET-1 on Day 21. KMUP-1 (3.6 mg/kg) maximally appeared at 0.25 hours in the plasma and declined to basal levels within 24 hours after sublingual administration. In isolated PA of MCT-treated rats, compared with control and pretreatment with l-NG-nitroarginine methyl ester (100 μM), KMUP-1 (0.1-100 μM) inhibited ET-1 (0.01 μM)-induced vasoconstriction. Endothelium-denuded PA sustained higher contractility in the presence of KMUP-1. In a 24-hour culture of smooth muscle cells (i.e., PA smooth muscle cells or PASMCs), KMUP-1 (0.1-10 μM) inhibited RhoA- and ET-1-induced RhoA activation. KMUP-1 prevented MCT-induced PAH, PA wall thickening, and RVH by enhancing eNOS and suppressing ET-1/ROCKII expression. In vitro, KMUP-1 inhibited ET-1-induced PA constriction and ET-1-dependent/independent RhoA activation of PASMCs. In summary, KMUP-1 attenuates ET-1-induced/ET-1-mediated PA constriction, and could thus aid in the treatment of PAH caused by MCT.

Topics: Animals; Blood Pressure; Body Weight; Cyclic GMP-Dependent Protein Kinases; Disease Models, Animal; Endothelin-1; Guanylate Cyclase; Heart Rate; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; In Vitro Techniques; Male; Monocrotaline; Nitric Oxide Synthase Type III; Piperazines; Piperidines; Pulmonary Artery; Purines; Rats, Wistar; Receptors, Cytoplasmic and Nuclear; Receptors, G-Protein-Coupled; rho-Associated Kinases; rhoA GTP-Binding Protein; Signal Transduction; Sildenafil Citrate; Soluble Guanylyl Cyclase; Sulfonamides; Vasoconstriction; Xanthines

Dietary intake of fructose and sucrose can cause development of metabolic and cardiovascular disorders. The consequences of high-fructose corn syrup (HFCS), a commonly consumed form of fructose and glucose, have poorly been examined. Therefore, in this study, we investigated whether HFCS intake (10% and 20% beverages for 12 weeks) impacts vascular reactivity to insulin and endothelin-1 in conjunction with insulin receptor substrate-1(IRS-1), endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS) mRNA/proteins levels in aorta of rats. At challenge, we tested the effectiveness of resveratrol (28-30 mg/kg body weight/day) on outcomes of HFCS feeding. HFCS (20%) diet feeding increased plasma triglyceride, VLDL, cholesterol, insulin and glucose levels, but not body weights of rats. Impaired nitric oxide-mediated relaxation to insulin (10⁻⁹ to 3×10⁻⁶ M), and enhanced contraction to endothelin-1 (10⁻¹¹ to 10⁻⁸ M) were associated with decreased expression of IRS-1 and eNOS mRNA and protein, but increased expression of iNOS, in aortas of rats fed with HFCS. Resveratrol supplementation restored many features of HFCS-induced disturbances, probably by regulating eNOS and iNOS production. In conclusion, dietary HFCS causes vascular insulin resistance and endothelial dysfunction through attenuating IRS-1 and eNOS expressions as well as increasing iNOS in rats. Resveratrol has capability to recover HFCS-induced disturbances.

Topics: Animals; Body Weight; Cholesterol, VLDL; Endothelin-1; Fructose; Gene Expression; Insulin; Insulin Receptor Substrate Proteins; Insulin Resistance; Male; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Rats; Rats, Wistar; Resveratrol; RNA, Messenger; Stilbenes; Sweetening Agents; Triglycerides

The aim of this study was to test the insulin-like growth factor-I (IGF-I) as a neuroprotective agent in a rat model for ischemic stroke and to compare its neuroprotective effects in conscious normotensive and spontaneously hypertensive rats. The effects of subcutaneous IGF-I injection were investigated in both rat strains using the endothelin-1 rat model for ischemic stroke. Motor-sensory functions were measured using the Neurological Deficit Score. Infarct size was assessed by Cresyl Violet staining. Subcutaneous administration of IGF-I resulted in significantly reduced infarct volumes and an increase in motor-sensory functions in normotensive rats. In these rats, IGF-I did not modulate blood flow in the striatum and had no effect on the activation of astrocytes as assessed by GFAP staining. In hypertensive rats, the protective effects of IGF-I were smaller and not always significant. Furthermore, IGF-I significantly reduced microglial activation in the cortex of hypertensive rats, but not in normotensive rats. More detailed studies are required to find out whether the reduction by IGF-I of microglial activation contributes to an impairment IGF-I treatment efficacy. Indeed, we have shown before that microglia in hypertensive rats have different properties compared to those in control rats, as they exhibit a reduced responsiveness to ischemic stroke and lipopolysaccharide.

Topics: Animals; Body Weight; Brain Ischemia; Endothelin-1; Glial Fibrillary Acidic Protein; Glucose; Humans; Hypertension; Immunohistochemistry; Injections, Subcutaneous; Insulin-Like Growth Factor I; Laser-Doppler Flowmetry; Macrophage Activation; Male; Microglia; Nervous System Diseases; Neuroprotective Agents; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Recombinant Proteins; Stroke; Telemetry

1. Two experiments were conducted to determine if in ovo and in-feed arginine (ARG) supplementation is effective in the prevention of pulmonary hypertension syndrome (PHS) in broiler chickens reared at high altitude. 2. In Experiment I, a total of 300 fertile eggs were divided into two equal groups. On d 5 of incubation, one group was injected with 0.5 ml of ARG (20 mg/ml) and the other remained untreated and served as controls. After hatching, male chicks (64 chickens per treatment) were selected and given a commercial maize-soyabean meal diet up to 48 d of age. 3. In Experiment II, a total of 128 male broiler chickens (Ross 308) were randomly assigned to two treatments, a control group that were fed on a basal diet that met ARG requirements and the second was fed on the basal diet supplemented with 1.5 g ARG per kg of diet. 4. Cumulative mortality from ascites was recorded in both experiments. Results from Experiment I indicated that in ovo injection of ARG significantly decreased ascites mortality of broilers (18.8 vs. 43.8%). Results from Experiment II showed a similar effect so that ascites mortality in the group that were given Arg supplement was significantly lower than the control (28.1 vs. 43.8%).

Topics: Animals; Arginine; Ascites; Body Weight; Chi-Square Distribution; Chickens; Dietary Supplements; Endothelin-1; Hypertension, Pulmonary; Male; Nitric Oxide; Ovum; Poultry Diseases; Random Allocation; Thyroid Hormones

To observe the influence of high blood glucose fluctuation on the endothelial function of type 2 diabetes mellitus (T2DM) rats and the effects of Panax Quinquefolius Saponin (PQS) of stem and leaf.. The T2DM model was induced by intraperitoneal injection of a small dose of streptozotocin (STZ, 35 mg/kg) plus high fat and high caloric laboratory chow. Then, diabetic rats were divided into steady high blood glucose (SHG) group and fluctuant high blood glucose (FHG) group according to fasting blood glucose coefficient of variation (FBG-CV), and then, the FHG group rats were divided into 4 groups according to the level of FBG-CV and fasting blood glucose: PQS 30 mg/(kg·d) group, PQS 60 mg/(kg·d) group, metformin hydrochloride control (MHC) group, and FHG control group, 10 in each group. Meanwhile, 10 rats without any treatment were used as normal control (NOR) group. Eight weeks later, the aortic arteries histology, plasma hepatocyte growth factor (HGF), and serum nitric oxide (NO), endothelin-1 (ET-1), tumor necrosis factor α (TNF-α), and soluble intercellular adhesion molecule 1 (sICAM-1) were measured.. In comparison with the NOR group, the level of plasma HGF and serum NO, ET-1 and TNF-α, and sICAM-1 in SHG and FHG control groups were all significantly increased (P<0.01); in comparison with the SHG group, plasma HGF and serum NO, ET-1, TNF-α, and sICAM-1 in FHG group were all significantly increased further (P<0.01 or P<0.05); meanwhile, in comparison with the FHG control group, the level of plasma HGF and serum NO, ET-1, TNF-α, and sICAM-1 in PQS and MHC groups were all decreased significantly (P<0.01). However, comparison of the aortic arteries histology among groups showed no significant differences either before or after treatment.. Blood glucose fluctuation could facilitate the development of vascular endothelial dysfunction in T2DM rats, while PQS could improve the endothelial function of T2DM rats with high blood glucose fluctuation, which may be related to its effects of relieving vessel stress, decreasing vasoconstrictor ET-1 production, preventing compensated increase of NO, and reducing inflammatory reaction.

Topics: Animals; Aorta; Blood Glucose; Body Weight; Diabetes Mellitus, Type 2; Endothelin-1; Endothelium, Vascular; Hepatocyte Growth Factor; Intercellular Adhesion Molecule-1; Male; Nitric Oxide; Panax; Plant Leaves; Plant Stems; Rats; Saponins; Solubility; Tumor Necrosis Factor-alpha

To investigate the effect of a short-term yoga-based lifestyle intervention on risk factors for cardiovascular disease (CVD) and markers of inflammation and endothelial function in overweight and obese men.. Nonrandomized prospective lifestyle intervention study with pre-post design. SETTING AND LOCATION: Integral Health Clinic, an outpatient facility providing yoga-based lifestyle intervention programs for prevention and management of chronic diseases.. Overweight and obese men (n=51) were enrolled in the study. Subjects who were physically unable to participate and those participating in other interventions were excluded from the study.. A pretested intervention program including asanas (physical postures), pranayama (breathing exercises), group discussions, lectures, and individualized advice.. The primary outcome measure was weight loss, and the secondary outcome measures were clinical and laboratory correlates of CVD risk, levels of interleukin-6 (IL-6), adiponectin, and endothelin-1 (ET-1).. Men (n=51, body mass index [BMI] 26.26±2.42 kg/m(2)) were enrolled and underwent a yoga-based lifestyle intervention for 10 days. Of 51 subjects, 30 completed the study. There was a significant reduction in weight from Baseline to Day 10 (74.60±7.98, 72.69±8.37 kg, p<0.001, respectively), BMI (26.26±2.42, 25.69±2.47 kg/m(2), p<0.001, respectively), and systolic BP (121.73±11.58, 116.73±9.00, p=0.042, respectively). There was a significant reduction in plasma IL-6 from Baseline to Day 10 (median 2.24 vs. 1.26 pg/mL, respectively, p=0.012). There was a significant increase in the plasma adiponectin from Baseline to Day 10 (median 4.95 vs. 6.26 μg/mL, respectively, p=0.014). Plasma ET-1 level remained unchanged.. These findings suggest that even a short-term yoga-based lifestyle intervention may be an important modality to reduce the risk for CVD as indicated by weight loss, reduction in systolic blood pressure, an increase in adiponectin, and decrease in IL-6 in overweight and obese men.

Topics: Adiponectin; Adolescent; Adult; Blood Pressure; Body Mass Index; Body Weight; Cardiovascular Diseases; Endothelin-1; Humans; Interleukin-6; Life Style; Lipoproteins; Male; Middle Aged; Obesity; Overweight; Prospective Studies; Pulse; Risk Factors; Yoga; Young Adult

The objective of this article is to assess the effects of nebivolol on resistant vascular reactivity, ventricular hypertrophy and the renin-angiotensin system in spontaneously hypertension rats (SHR).. Rats were divided into: SHR treated with nebivolol (8 mg/kg, i.g.)/atenolol(80 mg/kg, i.g.); SHR control group; normotensive Wistar-Kyoto (WKY) control group. Vascular responses to KCl, noradrenaline (NA), endothelin-1 (ET-1), angiotensin II (Ang II), acetylcholine (ACh) and sodium nitroprusside (SNP) were tested on the femoral and renal artery. Left ventricle weight/body weight ratio (LVW/BW) was measured. Ang II and angiotensin-converting enzyme (ACE) activity in plasma and the left ventricle were determined. Plasma renin activity (PRA) was quantified.. Systolic blood pressure was decreased after nebivolol treatment in SHR. Compared with WKY, the contractions to KCl, NA, Ang II and ET-1 were increased in SHR while the relaxation to ACh was impaired. LVW/BW was higher in SHR. Levels of Ang II and ACE activity in plasma and the left ventricle were increased in SHR, but PRA was similar in these groups. Compared with atenolol, nebivolol markedly improved resistant vascular reactivity and decreased LVW/BW and Ang II. But nebivolol had no influence on ACE activity and PRA in SHR.. Nebivolol treatment improved resistant arterial reactivity and reduced left ventricular hypertrophy and Ang II in SHR.

Topics: Acetylcholine; Angiotensin II; Animals; Benzopyrans; Blood Pressure; Body Weight; Endothelin-1; Ethanolamines; Femoral Artery; Hypertrophy, Left Ventricular; In Vitro Techniques; Male; Nebivolol; Nitroprusside; Norepinephrine; Rats; Rats, Inbred SHR; Renal Artery; Renin-Angiotensin System; Systole; Vascular Resistance

Leptin, the ob gene product, is a protein released from adipocytes and has been detected in fibrotic and cirrhotic livers. Leptin in brain has an inhibitory effect on food intake. Nonalcoholic steatohepatitis (NASH) is characterized by hyperleptinemia. This study explores the possible mechanisms of hyperleptinemia in relation to increased intrahepatic resistance (IHR) and portal hypertension in NASH cirrhotic rats. NASH cirrhotic rats with hyperleptinemia were induced in Zucker (fa/fa) and lean rats by feeding the animals a high fat/methionine-choline-deficient (HF/MCD) diet with and without exogenous administration of recombinant leptin. Portal venous pressure (PVP), IHR, plasma and hepatic levels of various substances, histopathology of the liver, the hepatic hydroxyproline content, and the expression of various hepatic protein and messenger RNA (mRNA) were measured. Hepatic microcirculatory dysfunction and the vasoconstrictive response to endothelin-1 were also observed using a liver perfusion system and intravital microscopy. Finally, the effect of leptin on hepatic stellate cells (HSCs) was evaluated. Both in HF/MCD-Zucker and HF/MCD+leptin lean rats, significant hepatic fibrogenesis and cirrhosis, marked portal hypertension, microcirculatory dysfunction, an enhanced vasoconstrictive response to endothelin-1, and an increased IHR were found to be associated with higher levels of hepatic endothelin-1 and endocannabinoids, expression levels of the cannabinoid type 1 receptor, endothelin-1 type A receptor (ET(A) R), activator protein-1, transforming growth factor beta (TGF-β)(1), osteopontin, tumor necrosis factor alpha (TNF-α), leptin, and the leptin receptor (OBRb). Interestingly, acute incubation of leptin directly increases the expression of ET(A) R, OBRb and activator protein-1 in HSCs.. An HF/MCD diet and hyperleptinemia increase hepatic endocannabinoids production, promote hepatic fibrogenesis, enhance the hepatic vasoconstrictive response to endothelin-1, and aggravate hepatic microcirculatory dysfunction; these events subsequently increase IHR and portal hypertension in NASH cirrhotic rats.

Topics: Animals; Biopsy, Needle; Body Weight; Cannabinoid Receptor Modulators; Diet, High-Fat; Disease Models, Animal; Disease Progression; Endocannabinoids; Endothelin-1; Fatty Liver; Hepatic Stellate Cells; Hypertension, Portal; Immunohistochemistry; Insulin Resistance; Kupffer Cells; Leptin; Liver; Microcirculation; Non-alcoholic Fatty Liver Disease; Random Allocation; Rats; Rats, Zucker; RNA, Messenger; Statistics, Nonparametric

Increased production of tumor necrosis factor-α (TNF-α) in chronic kidney disease may be involved in the progression of renal failure and injury, and cardiovascular disease. We investigated the effect of TNF-α neutralization on renal failure, inflammation and fibrosis, and blood pressure in rats with renal failure.. Renal failure was induced by renal mass reduction and the animals were treated with PEG-sTNFR1, a pegylated form of soluble TNF type 1 receptor that neutralizes TNF-α, for 6 weeks. Systolic, diastolic and mean arterial pressures were higher in renal failure rats that were associated with increased serum creatinine, albuminuria and renal injury comprised of blood vessel media hypertrophy, focal and segmental glomerulosclerosis, tubular atrophy and interstitial inflammation and fibrosis. These changes were associated with greater levels of TNF-α, transforming growth factor (TGF)-β1, nuclear transcription factor NF-ĸB and cytosolic phospho-IĸB-α, and inflammatory markers expression (ICAM-1, VCAM-1 and MCP-1). Moreover, endothelin (ET)-1 production was also increased, whereas nitric oxide (NO) release was decreased. TNF-α neutralization reduced hypertension, albuminuria and renal inflammation and fibrosis, which were coupled to a reduction in renal NF-ĸB activation, inflammatory markers expression, TGF-β1 and ET-1 production, and an increase in NO release.. Neutralization of TNF-α in rats with renal failure decreases NF-ĸB activity that is associated with a reduction in renal TGF-β1 and ET-1 production, and an improvement of NO release. These effects likely reduce renal inflammation and fibrosis, and blood pressure indicating a pivotal role for TNF-α, at least, in the progression of renal injury.

Topics: Animals; Blood Pressure; Body Weight; Chemokine CCL2; Disease Progression; Endothelin-1; Fibrosis; Heart Rate; Humans; Hypertension, Renal; Intercellular Adhesion Molecule-1; Male; NF-kappa B; Nitric Oxide Synthase Type III; Polyethylene Glycols; Rats; Rats, Sprague-Dawley; Receptors, Tumor Necrosis Factor, Type I; Renal Insufficiency, Chronic; Transforming Growth Factor beta1; Tumor Necrosis Factor-alpha; Vascular Cell Adhesion Molecule-1

The purpose was to investigate the effects of artificial cold air on cardiovascular risk in hypertensive subjects. An artificial cold air was simulated with hourly ambient temperature data of a real moderate cold air in China. Twenty-four male SHR rats were randomly divided into the minimum temperature (Tmin) group, the rewarming temperature (Tr) group and two concurrent control groups with six rats in each (Tmin and Tr represent two cold air time points, respectively). Tmin and Tr groups were exposed to the cold air that was stopped at Tmin and Tr, respectively. After cold air exposure, blood pressure, heart rate and body weight were monitored, blood was collected for the detection of some indexes like fibrinogen, total cholesterol and uric acid. Results demonstrated that blood pressure, whole blood viscosity, blood fibrinogen, total cholesterol and uric acid increased significantly both in the Tmin and Tr groups; low density lipoprotein/high density lipoprotein increased significantly only in Tr group; there was higher level of blood fibrinogen in the Tr group than the Tmin group; higher levels of creatine kinase-MB was found in both the Tmin and Tr groups. These results suggest that cold air may increase the cardiovascular risks in hypertensive subjects indirectly through its effects on the sympathetic nervous system and renin angiotensin system, blood pressure and atherosclerosis risk factors like blood viscosity and fibrinogen, lipids and uric acid in the blood.

Topics: Angiotensin II; Animals; Blood Chemical Analysis; Blood Pressure; Blood Viscosity; Body Weight; Cardiovascular Diseases; Cold Temperature; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Epinephrine; Fibrinogen; Heart Rate; Lipids; Male; Norepinephrine; Rats; Rats, Inbred SHR; Risk Factors; Vasoconstrictor Agents

The cardiac nitric oxide and endothelin-1 (ET-1) systems are closely linked and play a critical role in cardiac physiology. The balance between both systems is often disturbed in cardiovascular diseases. To define the cardiac effect of excessive ET-1 in a status of nitric oxide deficiency, we compared left ventricular function and morphology in wild-type mice, ET-1 transgenic (ET(+/+)) mice, endothelial nitric oxide synthase knockout (eNOS(-/-)) mice, and ET(+/+)eNOS(-/-) mice.. eNOS(-/-) and ET(+/+)eNOS(-/-) mice developed high blood pressure compared with wild-type and ET(+/+) mice. Left ventricular catheterization showed that eNOS(-/-) mice, but not ET(+/+)eNOS(-/-) , developed diastolic dysfunction characterized by increased end-diastolic pressure and relaxation constant tau. To elucidate the causal molecular mechanisms driving the rescue of diastolic function in ET(+/+)eNOS(-/-) mice, the cardiac proteome was analyzed. Two-dimensional gel electrophoresis coupled to mass spectrometry offers an appropriate hypothesis-free approach. ET-1 overexpression on an eNOS(-/-) background led to an elevated abundance and change in posttranslational state of antioxidant enzymes (e.g., peroxiredoxin-6, glutathione S-transferase mu 2, and heat shock protein beta 7). In contrast to ET(+/+)eNOS(-/-) mice, eNOS(-/-) mice showed an elevated abundance of proteins responsible for sarcomere disassembly (e.g., cofilin-1 and cofilin-2). In ET(+/+)eNOS(-/-) mice, glycolysis was favored at the expense of fatty acid oxidation.. eNOS(-/-) mice developed diastolic dysfunction; this was rescued by ET-1 transgenic overexpression. This study furthermore suggests that cardiac ET-1 overexpression in case of eNOS deficiency causes specifically the regulation of proteins playing a role in oxidative stress, myocytes contractility, and energy metabolism.

Topics: Animals; Blood Pressure; Blotting, Western; Body Weight; Diastole; Endothelin-1; Female; Immunohistochemistry; Male; Mice; Mice, Knockout; Mice, Transgenic; Natriuretic Peptide, Brain; Nitric Oxide Synthase Type III; Organ Size; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry

The aim of the paper is to investigate the effects of adiponectin in diabetic nephropathy; we used an adenovirus to over-express adiponectin (Ad-Adipo) in streptozotocin (STZ)-induced diabetic rats. Animals were injected with either Ad-Adipo or control Ad-lacZ at 10 weeks after STZ treatment, and at two weeks postadenovirus injection, renal function was assessed. The degree of proteinuria was significantly reduced in Ad-Adipo rats compared with Ad-lacZ rats. Consistent with this, the mRNA expression levels of nephrin and transforming growth factor β (TGF-β) were significantly increased and decreased in the renal cortex of Ad-Adipo rats, respectively. Moreover, adiponectin over-expression in STZ rats decreased markers of endothelial dysfunction, a feature of diabetic nephropathy disease progression. Endothelin 1 (ET-1), plasminogen activator inhibitor 1 (PAI-1) and inducible nitric oxide synthase (iNOS) mRNA expression levels were significantly reduced in the renal cortex of Ad-Adipo rats, respectively. Concurrently, mRNA expression levels of endothelial nitric oxide synthase (eNOS), a positive regulator of endothelial function, were significantly increased in the renal cortex of Ad-Adipo rats. We have shown that chronic hyperadiponectinemia significantly alleviated the progression of proteinuria in early stage diabetic nephropathy. The mechanism whereby adiponectin decreases proteinuria involves an increase in nephrin expression, and an improvement of the endothelial dysfunction due to decreases in ET-1 and PAI-1, and an increase in eNOS expression in the renal cortex. Thus, over-expression of adiponectin has beneficial effects on early stage diabetic nephropathy.

Topics: Adenoviridae; Adiponectin; Animals; Body Weight; Diabetes Mellitus, Experimental; Endothelin-1; Endothelium; Gene Expression Regulation; HEK293 Cells; Humans; Kidney Cortex; Male; Membrane Proteins; Mice; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Plasminogen Activator Inhibitor 1; Proteinuria; Rats; Rats, Wistar; RNA, Messenger; Transduction, Genetic; Transforming Growth Factor beta

At birth, the intestine becomes the sole site for nutrient absorption requiring a dramatic increase in blood flow. The vascular changes accompanying this transition have been partly characterized in mammals. We investigated, using wire myography, the developmental changes in chick mesenteric artery (MA) reactivity. Rings of the MA from 15-day (E15) and 19-day (E19) chicken embryos (total incubation 21 days) as well as non-fed 0-3-h-old (NH3h) and first-fed 1-day-old (NH1d) newly hatched chicks contracted in response to KCl, norepinephrine (NE), U46619, and endothelin (ET)-1 and relaxed in response to acetylcholine (ACh), sodium nitroprusside (SNP), and forskolin indicating the presence of electro- and pharmaco-mechanical coupling as well as cGMP- and cAMP-mediated relaxation. In ovo development and transition to ex ovo life was accompanied by alterations in the response of the MAs, but a different developmental trajectory was observed for each reactivity pathway tested. Thus, the contractile efficacy of KCl underwent a linear increase (E15 < E19 < NH3h < NH1d). The efficacy of NE and U46619 increased in ovo, but not ex ovo (E15 < E19 = NH3h = NH1d) and the efficacy of ET-1 peaked at E19 (E15 < E19 > NH3h = NH1d). The relaxations elicited by ACh (endothelium-dependent), SNP, and forskolin did not undergo significant developmental changes. In conclusion, the ability of chick MAs to constrict in response to pharmacological stimuli increases during the embryonic period, but no dramatic changes are induced by hatching or the first feeding. Maturation of vasodilator mechanisms precedes that of vasoconstrictor mechanisms. Alterations of the delicate balance between vasoconstrictors and vasodilators may play an important role in perinatal intestinal diseases.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Animals; Animals, Newborn; Body Weight; Chick Embryo; Chickens; Colforsin; Embryonic Development; Endothelin-1; Enzyme Inhibitors; Mesenteric Arteries; NG-Nitroarginine Methyl Ester; Nitroprusside; Norepinephrine; Oxadiazoles; Potassium Chloride; Quinoxalines; Vasoconstriction; Vasodilation

Pulmonary hypertension is characterized by increased vascular resistances, that could lead to right heart failure and death. Endothelin-1 (ET-1) is a peptide with strong vasoconstrictive and pro-fibrotic properties and is one of the main mediators of pulmonary hypertension. Aminaftone, a synthetic molecule derivative of 4-amynobenzoic acid, down-regulates ET-1 production in vitro by interfering with the transcription of the pre-pro-ET-1 gene. The aim of this study was to test whether the inhibition of ET-1 production by aminaftone attenuates the effects of pulmonary hypertension. Pulmonary hypertension was induced through s.c. injection of 60 mg/kg monocrotaline. The rats were randomly assigned to the following experimental groups: Control; Monocrotaline; Aminaftone 30 mg/kg/day; Aminaftone 150 mg/kg/day. After 5 weeks, mortality was significantly lower in the animals treated with aminaftone at both doses compared to monocrotaline alone. Aminaftone reduced plasma concentration of ET-1 and seemed to reduce right heart hypertrophy and the wall thickness of the pulmonary arteries at the highest dose. Aminaftone may represent a novel treatment strategy of pulmonary hypertension.

Topics: 4-Aminobenzoic Acid; Animals; Body Weight; Cardiomegaly; Disease Models, Animal; Endothelin-1; Hemodynamics; Hypertension, Pulmonary; Male; Monocrotaline; para-Aminobenzoates; Pulmonary Artery; Rats; Rats, Wistar; Survival Analysis

Rosmarinic acid (RA), a caffeic acid ester, has insulin-sensitizing and antioxidant effects in high fructose-fed model of insulin resistance (IR). This study investigated whether RA supplementation prevents cardiac abnormalities and hypertension in fructose-fed rats (FFR). Rats fed with fructose diet (60 g/100 g) for 60 days exhibited metabolic abnormalities and rise in plasma and cardiac lipids and whole body IR. The levels of cardiac antioxidants and plasma ferric reducing antioxidant power were significantly reduced in FFR concomitant with increased levels of lipid peroxidation and protein oxidation products. A significant rise in troponin T, creatine kinase-MB, aspartate transaminase, and lactate dehydrogenase in plasma of FFR was noted. RA supplementation to FFR (10 mg/kg from the 16th day) significantly improved insulin sensitivity, reduced lipid levels, oxidative damage, and the expression of p22phox subunit of nicotinamide adenine dinucleotide phosphate reduced oxidase, and prevented cardiac hypertrophy. Fructose-induced rise in blood pressure was also lowered by RA through decrease in endothelin-1 and angiotensin-converting enzyme activity and increase in nitric oxide levels. Histology revealed a reduction in myocardial damage in RA-supplemented FFR. These findings suggest that RA acts as a vasoactive substance and a cardioprotector through its antioxidant property. Thus, RA may be useful in reducing the cardiovascular risk associated with IR.

Topics: Animals; Antioxidants; Aspartate Aminotransferases; Blood Glucose; Blood Pressure; Body Weight; Cinnamates; Creatine Kinase, MB Form; Depsides; Dietary Carbohydrates; Endothelin-1; Fructose; Gene Expression; Heart; Hyperinsulinism; Hypertension; Insulin; Insulin Resistance; Kallikreins; L-Lactate Dehydrogenase; Lipid Metabolism; Lipids; Male; Myocardium; NADPH Oxidases; Nitrates; Nitric Oxide Synthase Type III; Organ Size; Oxidative Stress; Peptidyl-Dipeptidase A; Rats; Rats, Wistar; Rosmarinic Acid; Troponin C

Diabetic nephropathy is associated with cardiovascular morbidity. Angiotensin-converting enzyme (ACE) inhibitors provide imperfect renoprotection in advanced type 2 diabetes, and cardiovascular risk remains elevated. Endothelin (ET)-1 has a role in renal and cardiac dysfunction in diabetes. Here, we assessed whether combination therapy with an ACE inhibitor and ET(A) receptor antagonist provided reno- and cardioprotection in rats with overt type 2 diabetes. Four groups of Zucker diabetic fatty (ZDF) rats were treated orally from 4 (when proteinuric) to 8 mo with vehicle, ramipril (1 mg/kg), sitaxsentan (60 mg/kg), and ramipril plus sitaxsentan. Lean rats served as controls. Combined therapy ameliorated proteinuria and glomerulosclerosis mostly as a result of the action of ramipril. Simultaneous blockade of ANG II and ET-1 pathways normalized renal monocyte chemoattractant protein-1 and interstitial inflammation. Cardiomyocyte loss, volume enlargement, and capillary rarefaction were prominent abnormalities of ZDF myocardium. Myocyte volume was reduced by ramipril and sitaxsentan, which also ameliorated heart capillary density. Drug combination restored myocardial structure and reestablished an adequate capillary network in the presence of increased cardiac expression of VEGF/VEGFR-1, and significant reduction of oxidative stress. In conclusion, in type 2 diabetes concomitant blockade of ANG II synthesis and ET-1 biological activity through an ET(A) receptor antagonist led to substantial albeit not complete renoprotection, almost due to the ACE inhibitor. The drug combination also showed cardioprotective properties, which however, were mainly dependent on the contribution of the ET(A) receptor antagonist through the action of VEGF.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Glucose; Body Weight; Cell Count; Collagen Type III; Diabetes Mellitus, Type 2; Endothelin A Receptor Antagonists; Endothelin-1; Heart; Hemodynamics; Immunohistochemistry; Kidney; Kidney Function Tests; Male; Muscle Cells; Myocardium; Rats; Rats, Zucker; Real-Time Polymerase Chain Reaction; Receptors, Vascular Endothelial Growth Factor; Survival; Tyrosine; Vascular Endothelial Growth Factor A

Angiotensin (Ang) IV was reported to induce renal vasoconstriction or vasodilation in rats via AT1 or AT4 receptors, respectively, whereby the latter one has been identified to be the insulin-regulated aminopeptidase (IRAP). We investigated the effects of Ang IV on mean arterial pressure (MAP) and renal cortical blood flow (CBF) in AT1a, AT1b, AT2 receptor and IRAP knockout (-/-) mice and their corresponding wild-type littermates. Ang II, known as a renal vasoconstrictor in mice, was used as a reference.. MAP was recorded via a femoral catheter and CBF was measured using a light amplification by stimulated emission of radiation (LASER) Doppler probe; cortical vascular resistance (CVR) was calculated as MAP divided by CBF.. Baseline MAP, CBF and CVR in AT1a (-/-) mice were significantly lower than wild-type mice. AT2 (-/-) mice had a significantly higher baseline MAP, but similar CBF. In wild-type mice, Ang IV and Ang II induced dose-dependent pressor and renal vasoconstrictor responses, which were antagonized by the AT1 receptor blocker candesartan. These responses were almost completely absent in AT1a (-/-) mice, but were enhanced in AT2 (-/-) mice; responses in AT1b (-/-) and IRAP (-/-) mice were comparable to those in corresponding wild-type mice.. Ang IV mediates pressure and renal vasoconstrictor effects in mice via AT1a receptors, whereas IRAP/AT4 is not involved.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Base Sequence; Benzimidazoles; Biphenyl Compounds; Blood Pressure; Body Weight; DNA Primers; Endothelin-1; Hemodynamics; Kidney; Mice; Mice, Inbred C57BL; Mice, Knockout; Organ Size; Receptor, Angiotensin, Type 1; Tetrazoles; Vasoconstriction

Rho-kinase-dependent Ca2+ sensitization is an essential process for contraction of mammalian vascular smooth muscle but the information about its effects in non-mammalian vessels is scarce. We aimed to investigate, using the Rho-kinase inhibitor hydroxyfasudil, the potential role of the Rho-kinase pathway of Ca2+ sensitization in depolarization- and agonist-mediated contraction of chicken embryo (at day 19 of the 21 days of incubation) femoral arteries. Contraction elicited by KCl (125 mM) comprised two phases (phasic and tonic contraction), both of which were abolished in the absence of extracellular Ca2+. Hydroxyfasudil (10 microM) left the initial phasic component nearly intact but abolished the tonic component. Hydroxyfasudil also induced a marked impairment of the contractions elicited by phenylephrine (PE), the thromboxane A2 mimetic U46619, and endothelin-1. In contrast, inhibition of protein kinase C (PKC) by chelerythrine did not affect KCl- or PE-induced contractions, indicating lack of participation of PKC-mediated Ca2+ sensitization. Incubation under chronic hypoxia (15% O2 from day 0) impaired embryonic growth but did not significantly affect hydroxyfasudil-mediated relaxation. In summary, our findings are indicative of a role for Rho-kinase activity in depolarization- and agonist-induced force generation in chicken embryo femoral arteries.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Benzophenanthridines; Body Weight; Calcium; Chick Embryo; Egtazic Acid; Endothelin-1; Enzyme Inhibitors; Femoral Artery; Hypoxia; NG-Nitroarginine Methyl Ester; Oxadiazoles; Phenylephrine; Phorbol 12,13-Dibutyrate; Potassium Chloride; Protein Kinase C; Protein Kinase Inhibitors; Quinoxalines; rho-Associated Kinases; Vasoconstriction

Previous studies have showed that vascular endothelial growth factor (VEGF) displayed neurotrophic and neuroprotective activities. To examine whether target delivery of VEGF gene directly into brain may prevent ischemic brain damage, the VEGF expression adenoviral vectors, AVHP.VEGF-with 476bp of the human preproendothelin-1 (ppET-1) promoter and 35bp of the hypoxia-reponse element (HRE) driving VEGF expression and CMV.VEGF were transferred into hypoxic-induced ischemic (HI) rat brains. Seven-day-old rats that were underwent left carotid ligation followed by 2h of hypoxic stress (8% O(2) at 37 degrees C) were received VEGF adenoviral vectors or buffer (PBS) injection 3 days after HI. The body weight, VEGF expression, neuronal apoptosis, cerebral morphology and brain functional assays were performed between 7 and 28 days after HI. There were remarkable increases in the body weight and VEGF protein expression, and decrease in the number of TUNEL-positive cells in the VEGF vector groups as compared with PBS group. The VEGF vector groups also had better brain functional performs than PBS group. The better performs by the animals that received VEGF vectors may be directly linked to the inhibitory effect of VEGF on neuronal apoptosis because the animals had less neural loss in the cortex and hippocampal CA1 region as compared with PBS group. Overall, these results indicated that over-expression of VEGF in the brain exerted a neuroprotective effect and promoted neural functional recovery in neonatal rats after hypoxic-ischemic brain damage, suggesting that in vivo target VEGF gene transfer to brain may be a promising approch for the treatment of such implications.

Topics: Adenoviridae; Animals; Animals, Newborn; Apoptosis; Body Weight; Brain; Endothelin-1; Genetic Vectors; Humans; Hypoxia-Ischemia, Brain; Neurons; Promoter Regions, Genetic; Rats; Rats, Sprague-Dawley; Recovery of Function; Time Factors; Transduction, Genetic; Treatment Outcome; Vascular Endothelial Growth Factor A

Using perfused hearts from streptozotocin-induced long-term diabetic rats, we studied the coronary vasoconstrictor effect of the endothelin-1 (ET-1) precursor big ET-1 and also whether this response was modulated by N(epsilon)-(carboxymethyl)lysine (CML; a representative advanced glycation end product that is implicated in the pathogenesis of diabetic vasculopathy). The big ET-1-induced vasoconstriction (a) developed more rapidly (i.e., was greater in the first 30 min) in the diabetic group than in the age-matched controls, and (b) in each group was largely suppressed by phosphoramidon [nonselective endothelin-converting enzyme (ECE)/neutral endopeptidase (NEP) inhibitor] or CGS35066 (selective ECE inhibitor), but not by thiorphan (selective NEP inhibitor). The ET-1 release occurring after treatment with big ET-1, which was greater in diabetic coronary arteries than in the controls, was reduced by CGS35066. The dose-response curve for ET-1 was shifted to the left in the diabetics, so that at some lower doses of ET-1 the vasoconstriction was greater than in the controls. CML enhanced big ET-1- or ET-1-induced vasoconstriction in the controls, but not in the diabetics. Finally, the plasma level of CML was higher in diabetic than in control rats. These findings suggest (a) that the increased responsiveness to big ET-1 shown by diabetic coronary arteries may be attributable both to a more rapid conversion of big ET-1 to ET-1 (by ECE), allowing it to exert its contractile activity, and to an increased vascular sensitivity to ET-1, and (b) that CML may be at least partly responsible for the diabetes-associated enhancement of big ET-1-mediated coronary vasoconstriction.

Topics: Animals; Aspartic Acid Endopeptidases; Benzofurans; Blood Glucose; Body Weight; Coronary Vessels; Diabetes Mellitus, Experimental; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Endothelin-Converting Enzymes; Enzyme Inhibitors; Glycopeptides; Heart; Lipids; Lysine; Male; Metalloendopeptidases; Myocardium; Oligopeptides; Organ Size; Organophosphonates; Peptides, Cyclic; Perfusion; Piperidines; Rats; Rats, Wistar; Receptor, Endothelin A; Receptor, Endothelin B; Thiorphan; Vasoconstriction

We investigated the role of endothelin-1 (ET-1) in coronary microvascular spasm in a porcine model.. A flowmeter was implanted around the left anterior descending coronary artery (LAD), and epicardial coronary artery endothelial denudation (ED) was performed just distal to the flowmeter every 2 weeks (W) until 6 W in 10 pigs (ED group). Ten pigs were chronically treated with endothelin type A receptor (ET(A)) antagonist (TA-0201, 0.1 mg/kg/day, ED+ET(A) group), while neither ED nor administration of ET(A) antagonist was performed in 12 pigs (Control group). We assessed changes in LAD blood flow and the denuded site diameter induced by acetylcholine (ACh, 0.05 microg/kg i.c.).. In the ED group, administration of ACh to LAD induced zero flow without LAD diameter reduction at 8 W. In the ED+ET(A) group, the decrease in LAD blood flow response to ACh was suppressed. Chronic administration of TA-0201 suppressed ROS generation in the myocardium. Decreases of eNOS and intimal thickening were smaller in the TA-0201 administration group than the non-TA-0201 administration group.. Chronic administration of ET(A) receptor antagonist is effective to prevent coronary microvascular spasm.

Topics: Acetylcholine; Animals; Body Weight; Coronary Circulation; Coronary Sinus; Coronary Vasospasm; Coronary Vessels; Disease Models, Animal; Endothelin A Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Microcirculation; Nitric Oxide Synthase Type III; Pyrimidines; Reactive Oxygen Species; Receptor, Endothelin A; Sulfonamides; Sus scrofa; Vascular Resistance; Vasodilator Agents

Insulin-mediated glucose disposal is dependent on the vasodilator effects of insulin. In type 2 diabetes, insulin-stimulated vasodilation is impaired as a result of an imbalance in NO and ET-1 production. We tested the hypothesis that chronic voluntary wheel running (RUN) prevents impairments in insulin-stimulated vasodilation associated with obesity and type 2 diabetes independent of the effects of RUN on adiposity by randomizing Otsuka Long Evans Tokushima Fatty (OLETF) rats, a model of hyperphagia-induced obesity and type 2 diabetes, to 1) RUN, 2) caloric restriction (CR; diet adjusted to match body weights of RUN group), or 3) sedentary control (SED) groups (n = 8/group) at 4 wk. At 40 wk, NO- and ET-1-mediated vasoreactivity to insulin (1-1,000 μIU/ml) was assessed in the presence of a nonselective ET-1 receptor blocker (tezosentan) or a NO synthase (NOS) inhibitor [N(G)-nitro-L-arginine methyl ester (L-NAME)], respectively, in second-order arterioles isolated from the white portion of the gastrocnemius muscle. Body weight, fasting plasma glucose, and hemoglobin A1c were lower in RUN and CR than SED (P < 0.05); however, the glucose area under the curve (AUC) following the intraperitoneal glucose tolerance test was lower only in the RUN group (P < 0.05). Vasodilator responses to all doses of insulin were greater in RUN than SED or CR in the presence of a tezosentan (P < 0.05), but group differences in vasoreactivity to insulin with coadministration of L-NAME were not observed. We conclude daily wheel running prevents obesity and type 2 diabetes-associated declines in insulin-stimulated vasodilation in skeletal muscle arterioles through mechanisms that appear to be NO mediated and independent of attenuating excess adiposity in hyperphagic rats.

Topics: Adiposity; Animals; Arterioles; Blood Glucose; Body Composition; Body Weight; Caloric Restriction; Diabetes Mellitus, Type 2; Disease Models, Animal; Eating; Endothelin-1; Enzyme Inhibitors; Glycated Hemoglobin; Hyperphagia; Immunohistochemistry; Insulin; Insulin Resistance; Male; Motor Activity; Muscle, Skeletal; Nitric Oxide; Nitric Oxide Synthase Type III; Obesity; Phosphorylation; Rats; Rats, Inbred OLETF; Running; Time Factors; Vasodilation

Chronic inflammation has been implicated in the pathology of hypertension; however, the role for specific cytokines remains unclear. We tested whether tumor necrosis factor-α blockade with etanercept (Etan) reduces mean arterial pressure in a female mouse model of systemic lupus erythematosus (SLE). SLE is a chronic inflammatory disorder with prevalent hypertension. Thirty-week-old SLE (NZBWF1) and control mice (NZW/LacJ) received Etan (0.8 mg/kg SC weekly) for 4 weeks or vehicle. Mean arterial pressure (in millimeters of mercury) was increased in SLE mice (150±5 versus 113±5 in controls; P<0.05) and was lower in Etan-treated SLE mice (132±3) but not controls (117±5). Albuminuria (in micrograms per milligram of creatinine) was elevated in SLE mice (28 742±9032 versus 1075±883; P<0.05) and was lower in Etan-treated SLE mice (8154±3899) but not control animals (783±226). Glomerulosclerosis (in percentage of glomeruli) was evident in SLE mice (2.5±1.6 versus 0.0±0.0 in controls; P<0.05) and was ameliorated in Etan-treated SLE mice (0.1±0.1). Renal cortex CD68(+) cell staining (in percentage of area) was elevated in SLE mice (4.75±0.80 versus 0.79±0.12 in controls; P<0.05) and was lower in Etan-treated SLE mice (2.28±0.32) but not controls (1.43±0.25). Renal cortex NADPH oxidase activity (relative light units per milligram of protein) was higher in SLE mice compared with controls (10 718±1276 versus 7584±229; P<0.05) and lowered in Etan-treated SLE mice (6645±490). Renal cortex nuclear factor κB (phosphorylated and nonphosphorylated) was increased in SLE mice compared with controls and lower in Etan-treated SLE mice. These data suggest that TNF-α mechanistically contributes to the development of hypertension in a chronic inflammatory disease through increased renal nuclear factor κB, oxidative stress, and inflammation.

Topics: Albuminuria; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Blood Pressure; Body Weight; Chemokine CCL2; Creatinine; Disease Models, Animal; Endothelin-1; Etanercept; Female; Glomerulosclerosis, Focal Segmental; Hypertension; Immunoglobulin G; Kidney; Kidney Cortex; Lupus Erythematosus, Systemic; Mice; Mice, Inbred Strains; NADPH Oxidases; NF-kappa B; Receptors, Tumor Necrosis Factor; Tumor Necrosis Factor-alpha

Hyperglycemia mediates endothelial cell dysfunction through a number of potential mechanisms that could result in the decrease of retinal blood flow early in diabetes. The aim of this study was to explore the role of endothelin receptor A (ET(A)) in the early decrease of retinal blood flow in diabetic mice. Diabetes was induced by streptozotocin, then ∼1 wk later the mice were administered drinking water with or without the ET(A) receptor antagonist atrasentan (7.5mg/kg/day) for the following 3 weeks. Non-diabetic age-matched mice with or without atrasentan were included as controls. For each mouse, measurements of retinal vascular diameters and red blood cell (RBC) velocities were obtained via intravital microscopy for the 5-7 feed arterioles (and draining venules) extending out of (and into) the optic disk, and from these values, flow rates and wall shear rates were calculated. Additionally, the number of retinal capillaries was counted by fluorescent immunostaining of platelet-endothelial cell adhesion molecule-1 (PECAM-1). Diabetes induced statistically significant decreases in RBC velocity, flow rate, and wall shear rate, with these alterations partially inhibited by atrasentan. No changes were observed in PECAM-1 expression among groups. The changes induced by diabetes, and the attenuation provided by atrasentan, were greater in the smaller retinal arterioles. In summary, ET(A) appears to play a role in the early decreases in retinal blood flow in a mouse model of diabetes.

Topics: Administration, Oral; Animals; Atrasentan; Blood Flow Velocity; Blood Glucose; Body Weight; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Endothelin A Receptor Antagonists; Endothelin-1; Fluorescent Antibody Technique, Indirect; Male; Mice; Mice, Inbred C57BL; Platelet Endothelial Cell Adhesion Molecule-1; Pyrrolidines; Regional Blood Flow; Retinal Vessels

Decrease of both visceral fat (surgery, physical exercise) and subcutaneous fat (liposuction) is accompanied by improvement of insulin sensitivity.. In this study, metabolic variables (glucose, insulin, high-density lipoprotein-cholesterol, triglycerides, aspartate aminotransferase, alanine aminotransferase, uric acid, ferritin) and adhesion molecules (ICAM-1, entothelin-1, E-selectin) were determined in 126 morbidly obese subjects before and 1 year after bariatric restrictive surgery (laparoscopic gastric banding) and correlated with anthropometric measures, i.e., body mass index (BMI) and waist circumference (waist), and with echographic measures of thickness of visceral (usVT) and subcutaneous (usST) abdominal fat.. Under basal conditions and after 1 year, metabolic variables correlated with BMI and waist (r from 0.157 to 0.507, p from 0.0182 to 0.0001) and with usVT (r from 0.211 to 0.512, p from 0.05 to 0.0001); insulin also correlated with usST, and adhesion molecules only correlated with BMI and usVT (r from 0.341 to 0.502, p from 0.0066 to 0.0001). Changes of metabolic variables correlated with changes of BMI and waist (r from 0.163 to 0.356, p from 0.0328 to 0.0001) and with usVT changes (r from 0.211 to 0.361, p from 0.0339 to 0.0002); changes of adhesion molecules only correlated with BMI and usVT changes (r from 0.227 to 0.361, p from 0.0444 to 0.0108). Changes of metabolic variables and of adhesion molecules virtually never correlated with changes of usST.. These data indicate that in morbid obesity, most metabolic abnormalities are associated with visceral fat and that their improvements after weight loss are associated with decrease of visceral fat.

Topics: Adolescent; Adult; Aged; Blood Glucose; Body Fat Distribution; Body Mass Index; Body Weight; E-Selectin; Endothelin-1; Female; Gastroplasty; Humans; Insulin; Intercellular Adhesion Molecule-1; Intra-Abdominal Fat; Male; Middle Aged; Obesity, Morbid; Regression Analysis; Subcutaneous Fat, Abdominal; Ultrasonography; Weight Loss; Young Adult

Ingestion by mice of dextran sodium sulfate (DSS) induces colonic vasoconstriction and inflammation, with some of the effects potentially mediated by the vasoconstrictor endothelin-1 (ET-1).. In this study, mice given 5% 40 kD DSS for 5-6 days had elevated colonic immunostaining for ET-1 and platelet endothelial cell adhesion molecule-1 (PECAM-1). Increased ET-1 can induce microvascular constriction; however, the increase in PECAM-1 is consistent with angiogenesis that could decrease flow resistance.. Our measurements of intestinal blood flow, via infused microspheres, suggests that these 2 factors may offset each other, with only a nonsignificant tendency for a DSS-induced decrease in flow. Daily administration of the endothelin converting enzyme inhibitor SM-19712 (15 mg/kg) attenuated DSS-induced increases in colonic immunostaining of ET-1 and PECAM-1.. SM-19712 attenuated histologic signs of tissue injury and inflammation induced by DSS, and decreased the extent of loose stools and fecal blood. However, the inhibitor did not significantly decrease DSS-induced colon shortening or tissue levels of myeloperoxidase (an indicator of neutrophil infiltration).

Topics: Animals; Aspartic Acid Endopeptidases; Blood Pressure; Body Weight; Colitis; Colon; Dextran Sulfate; Disease Models, Animal; Endothelin-1; Endothelin-Converting Enzymes; Enzyme Inhibitors; Ileum; Metalloendopeptidases; Mice; Mice, Inbred C57BL; Organ Size; Peroxidase; Platelet Endothelial Cell Adhesion Molecule-1; Sulfonamides; Sulfonylurea Compounds; Vasoconstriction

1 This study examined the role of 20-hydroxyeicosatetraenoic (20-HETE) in altering vascular function in streptozotocin (STZ)-induced diabetic rats. 2 The expression of CYP4A protein and the formation of 20-HETE were elevated in the kidney, but not in the renal or mesenteric vasculature, of diabetic animals. The vasoconstrictor responses to norepinephrine (NE), endothelin-1 (ET-1), and angiotensin II (Ang II) were significantly enhanced in the isolated perfused mesenteric vascular bed and renal artery segments of diabetic rats. Chronic treatment of the diabetic rats with 1-aminobenzotriazole (ABT, 50 mg kg(-1) alt(-1) diem) or N-hydroxy-N'-(4-butyl-2-methylphenyl) formamidine (HET0016, 2.5 mg kg(-1) day(-1)) attenuated the responses to these vasoconstrictors in both vascular beds. 3 The synthesis of 20-HETE in renal microsomes was reduced by >80% confirming that the doses of ABT and HET0016 were sufficient to achieve system blockade. Addition of HET0016 (1 microM) in vitro also normalized the enhanced vascular responsiveness of renal and mesenteric vessels obtained from diabetic animals to NE and inhibited the formation of 20-HETE by >90% while having no effect on the formation of epoxides. Vasodilator responses to carbachol and histamine were reduced in the mesenteric vasculature, but not in renal arteries, of diabetic rats. Treatment of the diabetic animals with HET0016 improved vasodilator responses in both vascular beds. Vascular sensitivity to exogenous 20-HETE was elevated in the mesenteric bed of diabetic animals compared to controls. 4 These results suggest that 20-HETE contributes to the elevation in vascular reactivity in diabetic animals. This effect is not due to increased vascular expression of CYP4A but may be related to either enhanced agonist-induced release of substrate (arachidonic acid) by the CaMKII/Ras-GTPase system and/or elevated vascular responsiveness to 20-HETE by the CaMKII/Ras-GTPase system and/or elevated vascular responsiveness to 20-HETE.

Topics: Amidines; Angiotensin II; Animals; Blood Glucose; Body Weight; Carbachol; Cytochrome P-450 CYP4A; Diabetes Mellitus, Experimental; Endothelin-1; Enzyme Inhibitors; Histamine; Hydroxyeicosatetraenoic Acids; Kidney; Male; Mesenteric Arteries; Microsomes; Nitroprusside; Norepinephrine; Perfusion; Rats; Rats, Wistar; Renal Artery; Triazoles; Vasoconstriction; Vasodilation

We investigated whether the chronic treatment with raloxifene, a selective estrogen receptor modulator, prevents the development of monocrotaline-induced pulmonary hypertension in ovary-intact and ovariectomized female rats. Four weeks after a single subcutaneous injection of monocrotaline (60 mg/kg), right ventricular systolic pressure, right ventricle-to-left ventricle plus septal weight ratio, pulmonary arterial medial thickening and endothelin-1 levels in right ventricular tissue increased significantly in both female rats, compared with saline-treated control rats. These monocrotaline-induced alterations were much greater in ovariectomized rats than the changes in intact females. Daily oral administration of raloxifene (10 mg/kg/day for 4 weeks) significantly attenuated the increase in right ventricular systolic pressure to the same levels in both groups of animals, but raloxifene suppressed the increases in right ventricle-to-left ventricle plus septal weight ratio and pulmonary arterial medial thickness more efficiently in ovariectomized females than the case with intact females. In addition, raloxifene completely suppressed the increase in right ventricular endothelin-1 levels in ovariectomized rats, but not in intact females. These data suggest that chronic treatment with raloxifene effectively prevents the development of monocrotaline-induced pulmonary hypertension in ovariectomized female rats than in intact females, at least in part, by suppressing right ventricular endothelin-1 overproduction.

Topics: Animals; Blood Pressure; Body Weight; Endothelin-1; Female; Heart Ventricles; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Lung; Monocrotaline; Organ Size; Ovariectomy; Pulmonary Artery; Raloxifene Hydrochloride; Rats; Rats, Sprague-Dawley; Receptors, Estrogen; Substrate Specificity; Time Factors; Ventricular Dysfunction, Right

Acute kidney injury (AKI) in septic patients drastically increases the mortality to 50-80%. Sepsis is characterized by hemodynamic perturbations as well as overwhelming induction of proinflammatory cytokines. Since ghrelin has been shown to have anti-inflammatory properties, we hypothesized that ghrelin may afford renal protection during endotoxemia-induced AKI. Studies were conducted in a normotensive endotoxemia-induced AKI model in mice by intraperitoneal injection of 3.5 mg/kg LPS. Serum ghrelin levels were increased during endotoxemia accompanied by increased ghrelin receptor (GHSR-1a) protein expression in the kidney. Ghrelin administration (1.0 mg/kg sc 6 h and 30 min before and 14 h after LPS) significantly decreased serum cytokine levels (TNF-alpha, IL-1beta, and IL-6) and serum endothelin-1 levels which had been induced by LPS. The elevated serum nitric oxide (NO) levels and renal inducible NO synthase expression were also decreased by ghrelin. Renal TNF-alpha levels were also increased significantly in response to LPS and ghrelin significantly attenuated this increase. When administrated before LPS, ghrelin protected against the fall in glomerular filtration rate at 16 h (172.9 +/- 14.7 vs. 90.6 +/- 15.2 microl/min, P < 0.001) and 24 h (147.2 +/- 20.3 vs. 59.4 +/- 20.7 microl/min, P < 0.05) as well as renal blood flow at 16 h (1.65 +/- 0.07 vs. 1.47 +/- 0.04 ml/min, P < 0.01) and 24 h (1.56 +/- 0.08 vs. 1.22 +/- 0.03 ml/min, P < 0.05) after LPS administration without affecting mean arterial pressure. Ghrelin remained renal protective even when it was given after LPS. In summary, ghrelin offered significant protection against endotoxemia-induced AKI. The renal protective effect of ghrelin was associated with an inhibition of the proinflammatory cytokines. Of particular importance was the suppression of TNF-alpha both in the circulation and kidney tissues. Thus, ghrelin may be a promising peptide in managing endotoxemia-induced AKI.

Topics: Acute Kidney Injury; Animals; Body Weight; Cyclic GMP; Endothelin-1; Endotoxemia; Escherichia coli Infections; Ghrelin; HMGB1 Protein; Kidney; Kidney Function Tests; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Nitric Oxide; Nitric Oxide Synthase Type II; Receptors, Ghrelin; Tumor Necrosis Factor-alpha

The effect of habitual exercise on vascular function, including central arterial distensibility and endothelial function, in obese subjects has not yet been clarified. We investigated whether aerobic exercise training affects central arterial distensibility and endothelial function in middle-age overweight and obese men. A total of 21 overweight and obese men (age 50 +/- 2 years, body mass index 30 +/- 1 kg/m(2)) completed a 12-week aerobic exercise intervention. Aerobic exercise training significantly reduced their body weight and resulted in a significant decrease in body mass index. After the weight-reduction exercise program, carotid arterial compliance (determined by simultaneous B-mode ultrasonography and arterial applanation tonometry on the common carotid artery) significantly increased; and the beta-stiffness index, an index of arterial compliance adjusted for distending pressure, significantly decreased. The concentrations of plasma endothelin-1, a potent vasoconstrictor peptide produced by vascular endothelial cells, significantly decreased and plasma nitric oxide (measured as the stable end product [nitrite/nitrate]), a potent vasodilator produced by vascular endothelial cells, significantly increased after the weight-reduction exercise program. In conclusion, weight reduction by aerobic exercise training in overweight and obese men increased the central arterial distensibility. This increase might contribute to the improvement in endothelial function, as assessed by a decrease in endothelin-1 and an increase in nitric oxide, after exercise training-induced weight loss.

Topics: Absorptiometry, Photon; Adult; Body Weight; Endothelin-1; Endothelium, Vascular; Exercise; Humans; Male; Manometry; Middle Aged; Nitric Oxide; Obesity; Overweight; Oxygen Consumption

The present study was designed to investigate whether the aqueous extract of rhubarb (AR) could prevent the development of atherosclerosis through regulating vascular inflammatory processes in rats fed with an atherogenic diet. AR significantly reduced plasma low-density lipoprotein-cholesterol, and increased plasma high-density lipoprotein-cholesterol in rats fed with an atherogenic diet. AR inhibited vascular expressions of endothelin-1 (ET-1) and endothelin-converting enzyme (ECE) induced in rats with an atherogenic diet. On the other hand, AR augmented the vascular expression of endothelial nitric oxide synthase (ecNOS) and restored vascular nitric oxide (NO) production. Furthermore, AR suppressed the elevated expression of vascular nuclear factor-kappaB (NF-kappaB) p65 as well as adhesion molecules, including intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin in rats fed with an atherogenic diet. Also, AR decreased endothelial expression of ICAM-1 and ET-1 in aorta. These results suggest that AR suppresses the development of atherosclerosis in the atherogenic-diet rat model through inhibiting vascular expressions of proinflammatory and adhesion molecules via the regulation of nitric oxide and endothelin system.

Topics: Animals; Aorta, Thoracic; Aspartic Acid Endopeptidases; Atherosclerosis; Blood Pressure; Body Weight; Cholesterol, LDL; Diet, Atherogenic; Endothelin-1; Endothelin-Converting Enzymes; Intercellular Adhesion Molecule-1; Male; Metalloendopeptidases; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase Type III; Plant Extracts; Rats; Rats, Sprague-Dawley; Rheum

This study was designed to examine the effects of a high-fat, high-sucrose (HFHS) diet on vascular and metabolic actions of insulin. Male rats were randomized to receive an HFHS or regular chow diet for 4 wk. In a first series of experiments, the rats had pulsed Doppler flow probes and intravascular catheters implanted to measure blood pressure, heart rate, and regional blood flows. Insulin sensitivity and vascular responses to insulin were assessed during a euglycemic hyperinsulinemic clamp performed in conscious rats. In a second series of experiments, new groups of rats were used to examine skeletal muscle glucose transport activity and to determine in vitro vascular reactivity, endothelial nitric oxide synthase (eNOS) protein expression in muscle and vascular tissues and endothelin content, nitrotyrosine formation, and NAD(P)H oxidase protein expression in vascular tissues. The HFHS-fed rats displayed insulin resistance, hyperinsulinemia, hypertriglyceridemia, hyperlipidemia, elevated blood pressure, and impaired insulin-mediated renal and skeletal muscle vasodilator responses. A reduction in endothelium-dependent vasorelaxation, accompanied by a decreased eNOS protein expression in muscles and blood vessel endothelium, and increased vascular endothelin-1 protein content were also noted in HFHS-fed rats compared with control rats. Furthermore, the HFHS diet induced a reduced insulin-stimulated glucose transport activity in muscles and increased levels of NAD(P)H oxidase protein and nitrotyrosine formation in vascular tissues. These findings support the importance of eNOS protein in linking metabolic and vascular disease and indicate the ability of a Westernized diet to induce endothelial dysfunction and to alter metabolic and vascular homeostasis.

Topics: Animals; Blood Pressure; Blotting, Western; Body Weight; Deoxyglucose; Diet; Dietary Fats; Endothelin-1; Endothelium, Vascular; Fatty Acids, Nonesterified; Fluorescent Antibody Technique; Glucose Clamp Technique; Heart Rate; Insulin; Insulin Resistance; Male; Obesity; Organ Size; Rats; Rats, Sprague-Dawley; Sucrose; Triglycerides; Tyrosine; Vascular Diseases; Vascular Resistance

Chronic exposure to hypoxia, a common adverse consequence of most pulmonary disorders, can lead to a sustained increase in pulmonary arterial pressure (PAP), right ventricular hypertrophy, and is, therefore, closely associated with heart failure and increased mortality. Ghrelin, originally identified as an endogenous GH secretagogue, has recently been shown to possess potent vasodilator properties, likely involving modulation of the vascular endothelium and its associated vasoactive peptides. In this study we hypothesized that ghrelin would impede the pathogenesis of pulmonary arterial hypertension during chronic hypoxia (CH). PAP was continuously measured using radiotelemetry, in conscious male Sprague Dawley rats, in normoxia and during 2-wk CH (10% O(2)). During this hypoxic period, rats received a daily sc injection of either saline or ghrelin (150 microg/kg). Subsequently, heart and lung samples were collected for morphological, histological, and molecular analyses. CH significantly elevated PAP in saline-treated rats, increased wall thickness of peripheral pulmonary arteries, and, consequently, induced right ventricular hypertrophy. In these rats, CH also led to the overexpression of endothelial nitric oxide synthase mRNA and protein, as well as endothelin-1 mRNA within the lung. Exogenous ghrelin administration attenuated the CH-induced overexpression of endothelial nitric oxide synthase mRNA and protein, as well as endothelin-1 mRNA. Consequently, ghrelin significantly attenuated the development of pulmonary arterial hypertension, pulmonary vascular remodeling, and right ventricular hypertrophy. These results demonstrate the therapeutic benefits of ghrelin for impeding the pathogenesis of pulmonary hypertension and right ventricular hypertrophy, particularly in subjects prone to CH (e.g. pulmonary disorders).

Topics: Algorithms; Animals; Blood Glucose; Body Weight; Chronic Disease; Consciousness; Disease Progression; Drug Evaluation, Preclinical; Endothelin-1; Fatty Acids, Nonesterified; Ghrelin; Hemodynamics; Hypertension, Pulmonary; Hypoxia; Male; Nitric Oxide Synthase Type III; Rats; Rats, Sprague-Dawley; RNA, Messenger

We reported previously that simulating sleep apnea by exposing rats to eucapnic intermittent hypoxia (E-IH) causes endothelin-dependent hypertension and increases constrictor sensitivity to endothelin-1 (ET-1). In addition, augmented ET-1-induced constriction in small mesenteric arteries (sMA) is mediated by increased Ca(2+) sensitization independent of Rho-associated kinase. We hypothesized that exposing rats to E-IH augments ET-1-mediated vasoconstriction by increasing protein kinase C (PKC)-dependent Ca(2+) sensitization. In sMA, the nonselective PKC inhibitor GF-109203x (3 microM) significantly inhibited ET-1-stimulated constriction in E-IH arteries but did not affect ET-1-stimulated constriction in sham arteries. Phospholipase C inhibitor U-73122 (1 microM) also inhibited constriction by ET-1 in E-IH but not sham sMA. In contrast, the classical PKC (cPKC) inhibitor Gö-6976 (1 microM) had no effect on ET-1-mediated vasoconstriction in either group, but a PKCdelta-selective inhibitor (rottlerin, 3 microM) significantly decreased ET-1-mediated constriction in E-IH but not in sham sMA. ET-1 increased PKCdelta phosphorylation in E-IH but not sham sMA. In contrast, ET-1 constriction in thoracic aorta from both sham and E-IH rats was inhibited by Gö-6976 but not by rottlerin. These observations support our hypothesis that E-IH exposure significantly increases ET-1-mediated constriction of sMA through PKCdelta activation and modestly augments ET-1 contraction in thoracic aorta through activation of one or more cPKC isoforms. Therefore, upregulation of a PKC pathway may contribute to elevated ET-1-dependent vascular resistance in this model of hypertension.

Topics: Animals; Aorta, Thoracic; Blood Pressure; Body Weight; Carbon Dioxide; Diglycerides; Endothelin-1; Endothelium, Vascular; Enzyme Inhibitors; Hypoxia; In Vitro Techniques; Male; Mesenteric Arteries; Muscle Contraction; Muscle, Smooth, Vascular; Protein Kinase C-delta; Rats; Rats, Sprague-Dawley; Type C Phospholipases; Vasoconstriction

In the present study, we tested the hypothesis that ANG II causes a greater vasoconstriction in obese Zucker rats, a model of type 2 diabetes, with mild hypertension. Measurement of isometric tension in isolated aortic rings with intact endothelium revealed a modest but not significantly greater ANG II-induced contraction in obese than lean rats. Removal of endothelium or inhibition of nitric oxide (NO) synthase by N(G)-nitro-L-arginine methyl ester (L-NAME) enhanced 1) ANG II-induced contraction in both lean and obese rats, being significantly greater in obese rats (E(max) g/g tissue, denuded: lean 572 +/- 40 vs. obese 664 +/- 16; L-NAME: lean 535 +/- 14 vs. obese 818 +/- 23) and 2) ANG II sensitivity in obese compared with lean rats, as revealed by the pD(2) values. Endothelin-1 and KCl elicited similar contractions in the aortic rings of lean and obese rats. ACh, a NO-dependent relaxing hormone, produced greater relaxation in the aortic rings of obese than lean rats, whereas sodium nitroprusside, an NO donor, elicited similar relaxations in both rat strains. The expression of the ANG type 1 (AT(1)) receptor protein and mRNA in the endothelium-intact aorta was significantly greater in obese than lean rats, whereas the endothelium-denuded rings expressed modest but not significantly greater levels of AT(1) receptors in obese than lean rats. The endothelial NO synthase protein and mRNA expression levels were higher in the aorta of obese than lean animals. We conclude that, although ANG II produces greater vasoconstriction in obese rat aortic rings, enhanced endothelial AT(1) receptor-mediated NO production appears to counteract the increased ANG II-induced vasoconstriction, suggesting that arterial AT(1) receptor may not be a contributing factor to hypertension in this model of obesity.

Topics: Acetylcholine; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Aorta, Thoracic; Body Weight; Endothelial Cells; Endothelin-1; Enzyme Inhibitors; In Vitro Techniques; Losartan; Male; Muscle, Smooth, Vascular; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase Type III; Nitroprusside; Obesity; Potassium Chloride; Rats; Rats, Zucker; Receptor, Angiotensin, Type 1; RNA, Messenger; Vasoconstriction; Vasoconstrictor Agents; Vasodilator Agents

Dietary protein as casein (CAS) augments intrinsic acid production, induces endothelin-mediated kidney acidification, and promotes kidney injury. We tested the hypothesis that dietary CAS induces endothelin-mediated kidney injury through augmented intrinsic acid production. Munich-Wistar rats ate minimum electrolyte diets from age 8 to 96 weeks with 50 or 20% protein as either acid-inducing CAS or non-acid-inducing SOY. Urine net acid excretion and distal nephron net HCO3 reabsorption by in vivo microperfusion (Net J(HCO3)) were higher in 50 than 20% CAS but not 50 and 20% SOY. At 96 weeks, 50% compared the 20% CAS had higher urine endothelin-1 excretion (U(ET-1)V) and a higher index of tubulo-interstitial injury (TII) at pathology (2.25+/-0.21 vs 1.25+/-0.13 U, P<0.03), but each parameter was similar in 50 and 20% SOY. CAS (50%) eating NaHCO3 to reduce intrinsic acid production had lower Net J(HCO3), lower U(ET-1)V, and less TII. By contrast, 50% SOY eating dietary acid as (NH4)2SO4 had higher Net J(HCO3), higher U(ET-1)V, and more TII. Endothelin A/B but not A receptor antagonism reduced Net J(HCO3) in 50% CAS and 50% SOY+(NH4)2SO4 animals. By contrast, endothelin A but not A/B receptor antagonism reduced TII in each group. The data support that increased intake of acid-inducing dietary protein induces endothelin B-receptor-mediated increased Net J(HCO3) and endothelin A-receptor-mediated TII through augmented intrinsic acid production.

Topics: Acidosis, Renal Tubular; Acids; Animals; Bicarbonates; Body Weight; Bosentan; Caseins; Dietary Proteins; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Glomerular Filtration Rate; Glomerulosclerosis, Focal Segmental; Male; Phenylpropionates; Pyrimidines; Rats; Rats, Inbred Strains; Receptor, Endothelin A; Receptor, Endothelin B; Sulfonamides

Endothelin-1 (ET-1) is one of the most potent biologic vasoconstrictors. Nevertheless, transgenic mice that overexpress ET-1 exhibit normal BP. It was hypothesized that vascular effects of ET-1 may be antagonized by an increase of the endothelial counterpart of ET-1, nitric oxide (NO), which is produced by the endothelial NO synthase (eNOS). Therefore, cross-bred animals of ET transgenic mice (ET+/+) and eNOS knockout (eNOS-/-) mice and were generated, and BP and endothelial function were evaluated in these animals. Endothelium-dependent and -independent vascular function was assessed as relaxation/contraction of isolated preconstricted aortic rings. The tissue ET and NO system was determined in aortic rings by quantitative real-time PCR and Western blotting. Systolic BP was similar in ET+/+ and wild-type (WT) mice but was significantly elevated in eNOS-/- mice (117 +/- 4 mmHg versus 94 +/- 6 mmHg in WT mice; P < 0.001) and even more elevated in ET+/+ eNOS-/- cross-bred mice (130 +/- 4 mmHg; P < 0.05 versus eNOS-/-). Maximum endothelium-dependent relaxation was enhanced in ET+/+ mice (103 +/- 6 versus 87 +/- 4% of preconstriction in WT littermates; P < 0.05) and was completely blunted in eNOS-/- (-3 +/- 4%) and ET+/+ eNOS-/- mice (-4 +/- 4%), respectively. Endothelium-independent relaxation was comparable among all groups. Quantitative real-time PCR as well as Western blotting revealed an upregulation of the aortic ET(A) and ET(B) receptors in ET+/+ eNOS-/-, whereas eNOS was absent in aortic rings of eNOS-/- and ET+/+ eNOS-/- mice. ET-1 aortic tissue concentrations were similar in WT mice and ET+/+ eNOS-/- mice most probably as a result of an enhanced clearance of ET-1 by the upregulated ET(B) receptor. These data show for the first time that in transgenic mice that overexpress human ET-1, additional knockout of eNOS results in a further enhancement of BP as compared with eNOS-/- mice. The human ET+/+ eNOS-/- mice therefore represent a novel model of hypertension as a result of an imbalance between the vascular ET-1 and NO systems.

Topics: Acetylcholine; Animals; Aorta; Blood Pressure; Body Weight; Endothelin-1; Endothelium; Hypertension; Mice; Mice, Knockout; Mice, Transgenic; Nitric Oxide; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Organ Size; RNA, Messenger

To establish an ideal model of multiple organ injury of rats with severe acute pancreatitis (SAP).. SAP models were induced by retrograde injection of 0.1 mL/100 g 3.5% sodium taurocholate into the biliopancreatic duct of Sprague-Dawley rats. The plasma and samples of multiple organ tissues of rats were collected at 3, 6 and 12 h after modeling. The ascites volume, ascites/body weight ratio, and contents of amylase, endotoxin, endothelin-1 (ET-1), nitrogen monoxidum (NO), phospholipase A(2) (PLA(2)), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) in plasma were determined. The histological changes of multiple organs were observed under light microscope.. The ascites volume, ascites/body weight ratio, and contents of various inflammatory mediators in blood were higher in the model group than in the sham operation group at all time points [2.38 (1.10), 2.58 (0.70), 2.54 (0.71) vs 0.20 (0.04), 0.30 (0.30), 0.22 (0.10) at 3, 6 and 12 h in ascites/body weight ratio; 1582 (284), 1769 (362), 1618 (302) (U/L) vs 5303 (1373), 6276 (1029), 7538 (2934) (U/L) at 3, 6 and 12 h in Amylase; 0.016 (0.005), 0.016 (0.010), 0.014 (0.015) (EU/mL) vs 0.053 (0.029), 0.059 (0.037), 0.060 (0.022) (EU/mL) at 3, 6 and 12 h in Endotoxin; 3.900 (3.200), 4.000 (1.700), 5.300 (3.000) (ng/L) vs 41.438 (37.721), 92.151 (23.119), 65.016 (26.806) (ng/L) at 3, 6 and 12 h in TNF-alpha, all P < 0.01]. Visible congestion, edema and lamellar necrosis and massive leukocytic infiltration were found in the pancreas of rats of model group. There were also pathological changes of lung, liver, kidney, spleen, ileum, lymphonode, thymus, myocardium and brain.. This rat model features reliability, convenience and a high achievement ratio. Complicated with multiple organ injury, it is an ideal animal model of SAP.

Topics: Acute Disease; Amylases; Animals; Ascitic Fluid; Body Weight; Brain; Disease Models, Animal; Endothelin-1; Endotoxins; Feasibility Studies; Ileum; Interleukin-6; Kidney; Liver; Lymph Nodes; Male; Multiple Organ Failure; Myocardium; Nitric Oxide; Pancreas; Pancreatitis; Phospholipases A; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Severity of Illness Index; Taurocholic Acid; Thymus Gland; Time Factors; Tumor Necrosis Factor-alpha

Diabetic gastropathy is suggested to be the result of not only an autonomic neuropathy but also to disorder of the spontaneous rhythmic motility of the gastric smooth muscle. Attempts were made to investigate the alteration of the effects of endothelin-1 (ET-1), which is known to enhance the spontaneous activity of gastrointestinal smooth muscle, on gastric activity in streptozotocin (STZ)-induced diabetic rats. STZ-induced diabetic rats were prepared by the injection of Sprague-Dawley (SD) rats with STZ (i.p.). Isometric mechanical responses were recorded in isolated circular smooth muscle strips of the stomach antrum, to measure changes in the rhythmicity of the smooth muscle. ET-1 (10 nM) significantly elevated the resting tension and the frequency of spontaneous contraction, but did not alter the amplitude of the spontaneous oscillatory contractions in normal rats. In diabetic rats, ET-1 elevated the resting tension, and spontaneous contractions were increased in frequency, however they were decreased in amplitude. In normal rats, sarafotoxin S6c (S6c, 10 nM), a selective ET(B) receptor agonist, elevated the resting tension slightly and increased both the frequency and amplitude of the spontaneous contractions. However, S6c significantly elevated the resting tension alone in STZ-induced diabetic rats. Selective stimulation of endothelin type A (ET(A)) receptors with ET-1, in the presence of a selective antagonist of ET(B) receptors, produced similar responses in the gastric muscle of both normal and diabetic rats. These results indicate that ET-1 elevates the resting tension and increases the frequency of the spontaneous oscillatory contractions in both normal and STZ-induced diabetic rats, to a similar extent. However, the specific actions on ET(B) receptors were quite different between the two: the elevating actions on the resting tension were much greater in STZ-diabetic rats than in normal rats. The results suggested the facilitation of ET(B) receptor signaling in the antrum during the pathogenesis of diabetic gastropathy.

Topics: Animals; Blood Glucose; Body Weight; Diabetes Complications; Diabetes Mellitus, Experimental; Endothelin-1; Muscle Contraction; Muscle, Smooth; Pyloric Antrum; Rats; Rats, Sprague-Dawley; Receptor, Endothelin B; Stomach; Stomach Diseases

Nitric oxide (NO) is important for the homeostasis of organ functions. We studied the structural and functional changes in the cardiovascular (CV) and renal systems following early NO deprivation by various nonspecific and specific NO synthase (NOS) inhibitors: N-nitro-L-arginine methyl ester (L-NAME), N-nitro-L-arginine (L-NA), S-methyl-isothiourea (SMT), and L-N6-(1-iminoethyl)-lysine (L-Nil). The aim is to elucidate the involvement of NO through endothelial or inducible NOS (eNOS and iNOS). Drugs were given to spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar Kyoto rats (WKY) from a young age (5-wk-old). Physiological, biochemical, and pathological examinations were performed. L-NAME and L-NA treatment caused a rapid increase in tail cuff pressure (TCP). The TCP of SHR reached a malignant level within 30 days with signs of stroke, proteinuria [corrected] severe glomerular sclerosis, and moderate ventricular hypertrophy (VH). The plasma nitrite/nitrate was reduced, while creatinine, urea nitrogen and uric acid were elevated. The renal tissue cyclic guanosine monophosphate (cGMP) was decreased with an elevated collagen content. The numbers of sclerotic glomeruli, arteriolar and glomerular injury scores were markedly increased, accompanied by reduction in renal blood flow, filtration rate, and fraction. Plasma endothelin-1 was increased following L,-NAME or L-NA treatment for 10 days. The expression of eNOS and iNOS mRNA was depressed by L-NAME and L-NA. The relevant iNOS inhibitors, SMT and L-Nil depressed the iNOS expression, but did not produce significant changes in CV and renal systems. The continuous release of NO via the eNOS system provides a compensatory mechanism to prevent the genetically hypertensive rats from rapid progression to malignant phase. Removal of this compensation results in VH, stroke, glomerular damage, renal function impairment, and sudden death.

Topics: Animals; Blood Pressure; Blood Urea Nitrogen; Body Weight; Endothelin-1; Enzyme Inhibitors; Glomerular Filtration Rate; Hypertension; Isothiuronium; Kidney; Kidney Function Tests; Lysine; Muscle Weakness; NG-Nitroarginine Methyl Ester; Nitrates; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Nitrites; Nitroarginine; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Renal Circulation; Ventricular Function, Left

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor characterized to play a role in detection and adaptation to environmental stimuli. Genetic deletion of AhR results in hypertension, and cardiac hypertrophy and fibrosis, associated with elevated plasma angiotensin II (Ang II) and endothelin-1 (ET-1), thus AhR appears to contribute to cardiovascular homeostasis. In these studies, we tested the hypothesis that ET-1 mediates cardiovascular pathology in AhR null mice via ETA receptor activation. First, we determine the time courses of cardiac hypertrophy, and of plasma and tissue ET-1 expression in AhR wildtype and null mice. AhR null mice exhibited increases in heart-to-body weight ratio and age-related expression of cardiac hypertrophy markers, beta-myosin heavy chain (beta-MHC), and atrial natriuretic factor (ANF), which were significant at 2 months. Similarly, plasma and tissue ET-1 expression was significantly elevated at 2 months and increased further with age. Second, AhR null mice were treated with ETA receptor antagonist, BQ-123 (100 nmol/kg/day), for 7, 28, or 58 days and blood pressure, cardiac fibrosis, and cardiac hypertrophy assessed, respectively. BQ-123 for 7 days significantly reduced mean arterial pressure in conscious, catheterized mice. BQ-123 for 28 days significantly reduced the histological appearance of cardiac fibrosis. Treatment for 58 days significantly reduced cardiac mass, assessed by heart weight, echocardiography, and beta-MHC and ANF expression; and reduced cardiac fibrosis as determined by osteopontin and collagen I mRNA expression. These findings establish ET-1 and the ETA receptor as primary determinants of hypertension and cardiac pathology in AhR null mice.

Topics: Angiotensin II; Animals; Blood Pressure; Body Weight; Cardiomegaly; Disease Progression; Echocardiography; Endothelin A Receptor Antagonists; Endothelin-1; Fibrosis; Hypertrophy, Left Ventricular; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocytes, Cardiac; Organ Size; Peptides, Cyclic; Receptor, Endothelin A; Receptors, Aryl Hydrocarbon; RNA, Messenger

Changes in reactivity to phenylephrine in aortas isolated from 2-, 6-, and 10-week ethanol-treated rats and their age-matched control and isocaloric rats were investigated. Chronic ethanol consumption enhances the contractile response of endothelium-intact and -denuded rat aortic rings to phenylephrine, a response that is time-independent. Pretreatment with indomethacin reduced E(max) for phenylephrine in denuded aortas from ethanol-treated rats but not control or isocaloric rats. After indomethacin treatment, no differences in E(max) from phenylephrine were observed among the groups. SQ29548 ([1S-[1alpha-2alpha(Z)3alpha,4alpha]]-7-[3-[[(phenylamino)carbonyl]hydrazino]methyl]-7-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid), an antagonist of prostaglandin H(2)/thromboxane A(2) (TXA(2)) receptors, did not alter phenylephrine-induced contraction in control or isocaloric aortas. However, in ethanol-treated aortas, E(max) was reduced to control level. Moreover, phenylephrine-stimulated release of thromboxane B(2), a stable metabolite of TXA(2), was higher in tissues from ethanol-treated rats. Simultaneous measurement of the changes in [Ca(2+)](i) and contraction induced by phenylephrine showed that both parameters are higher in the rat aorta from ethanol-treated rats. CaCl(2)-induced contraction in free Ca(2+) solution containing phenylephrine was increased in ethanol-treated aortas. Additionally, the enhancement in CaCl(2)-induced contraction was prevented by SQ29548. The major contribution of the present study is that it demonstrates a detailed description of the mechanisms involved in the enhancement of phenylephrine-induced contraction in rat aorta from ethanol-treated rats. We provided evidence that this response was not different among the three periods of treatment employed in this study and that it is maintained by two mechanisms: an increased release of vascular smooth muscle-derived vasoconstrictor prostanoids (probably TXA(2)) and an enhanced extracellular Ca(2+) influx.

Topics: Animals; Aorta, Thoracic; Arachidonic Acid; Blood Glucose; Body Weight; Calcium; Cardiotonic Agents; Central Nervous System Depressants; Cytosol; Dose-Response Relationship, Drug; Endothelin-1; Endothelium, Vascular; Ethanol; Heart; Male; Muscle Contraction; Muscle, Smooth, Vascular; Nitric Oxide; Phenylephrine; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; Thromboxane A2

Walnut consumption is associated with reduced coronary vascular disease (CVD) risk; however, the mechanisms responsible remain incompletely understood. Recent clinical studies suggested that these mechanisms involve non-plasma lipid-related effects on endothelial function. Male Golden Syrian hamsters (12 groups, n=10-15) were fed for 26 wk atherosclerotic, high-fat, hyperlipidemic diets with increasing concentrations of whole walnuts (61-150 g/kg diet), or alpha-tocopherol (alpha-T, 8.1-81 mg/kg diet) and single diets with either walnut oil (32 g/kg diet) or pure gamma-tocopherol (gamma-T; 81 mg/kg diet) added. Aortic endothelin 1 (ET-1), an important endothelial regulator, was assayed as mRNA. Aortic cholesterol ester (CE) concentration along with other vascular stress markers (Cu/Zn and Mn superoxide dismutase, biliverdin reductase) and plasma lipid concentrations were determined. Hyperlipidemia (plasma LDL cholesterol approximately 6 times normal) occurred in all groups. Aortic CE concentration, a measure of atherosclerotic plaque, was highest in the lowest alpha-T only group and declined significantly with increasing alpha-T. The aortic CE of all walnut groups was decreased significantly relative to the lowest alpha-T only group but showed no dose response. The diets did not produce changes in the other vascular stress markers, whereas aortic ET-1 mRNA levels declined dramatically with increasing dietary walnuts (to a 75% reduction in the highest walnut content group compared with the lowest alpha-T group) but were unaltered in the alpha-T groups or gamma-T group. The study results are consistent with those of human walnut feeding studies and suggest that the mechanisms underlying those results are mediated in part by ET-1-dependent mechanisms. The contrasting results between the alpha-tocopherol or gamma-tocopherol diets and the walnut diets also make it unlikely that the non-plasma lipid-related CVD effects of walnuts are due to their alpha-tocopherol or gamma-tocopherol content. Finally, the results indicate that the walnut fat compartment is a likely location for the components responsible for the reduced aortic CE concentration.

Topics: Animal Feed; Animals; Aorta; Body Weight; Cholesterol Esters; Cricetinae; Diet, Atherogenic; Dietary Fats; Endothelin-1; Juglans; Lipoproteins; Male; Mesocricetus; Oxidoreductases Acting on CH-CH Group Donors; RNA, Messenger; Superoxide Dismutase

An impairment of cardiac norepinephrine (NE) reuptake via the neuronal NE transporter (NET) enhances the effects of increased cardiac NE release in heart failure patients. Increasing evidence suggests that aldosterone and endothelins promote sympathetic overstimulation of failing hearts. Salt-sensitive Dahl rats (DS) fed a high-salt diet developed arterial hypertension and diastolic heart failure as well as elevated plasma levels of endothelin-1 and NE. Cardiac NE reuptake and NET-binding sites, as assessed by clearance of bolus-injected [(3)H]NE in isolated perfused rat hearts and [(3)H]mazindol binding, were reduced. Treatment of DS with the mineralocorticoid receptor antagonist spironolactone preserved the plasma levels of endothelin-1 and NE, cardiac NE reuptake, and myocardial NET density. Moreover, the ventricular function and survival of spironolactone-treated DS were significantly improved compared with untreated DS. The alpha(1)-inhibitor prazosin decreased blood pressure in DS similar to spironolactone treatment, but did not normalize the plasma levels of endothelin-1 and NE, NE reuptake, or ventricular function. In a heart failure-independent model, Wistar rats that were infused with aldosterone and fed a high-salt diet developed impaired cardiac NE reuptake. Treatment of these rats with the endothelin A receptor antagonist darusentan attenuated the impairment of NE reuptake. In conclusion, spironolactone preserves NET-dependent cardiac NE reuptake in salt-dependent heart failure. Evidence is provided that aldosterone inhibits NET function through an interaction with the endothelin system. Selective antagonism of the mineralocorticoid and/or the endothelin A receptor might represent therapeutic principles to prevent cardiac sympathetic overactivity in salt-dependent heart failure.

Topics: Aldosterone; Animals; Body Weight; Echocardiography; Endothelin-1; Heart; Heart Ventricles; Hemodynamics; Male; Mineralocorticoid Receptor Antagonists; Models, Statistical; Myocardium; Neurons; Norepinephrine; Norepinephrine Plasma Membrane Transport Proteins; Organ Size; Perfusion; Rats; Rats, Inbred Dahl; Rats, Wistar; Salts; Sodium Chloride; Spironolactone

This study determined whether exercise training prevents pathological hypertrophy in the left ventricle by modulation of myocardial and apoptosis-associated genes. We used spontaneously hypertensive rats (n=15, non-exercise SHR), exercise-trained SHR (n=15, treadmill exercise for 12 weeks), and sedentary Wistar-Kyoto (WKY) rats (n=15). Exercise-trained SHR expressed adaptive changes such as reduced body weight, heart rate, blood pressures, left ventricle wall thickness, lipid profiles, and homocysteine level. The mRNA expression of angiotensin converting enzyme, endothelin-1, and brain natriuretic peptides in the heart was lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR, whereas mRNA expression of caveolin-3 and eNOS in the heart was higher. Bcl-2 protein was higher in the exercise-trained SHR than in the WKY and the non-exercise SHR. In contrast, Bax protein levels were lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR. Furthermore, the levels of the active forms of caspase-3 (20 kDa) were lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR. These findings suggest that exercise training prevents pathological hypertrophy in the left ventricle by modulation of myocardial genes and that it interferes with a signal transduction pathway of apoptosis secondary to the pathological cardiac hypertrophy.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Blood Pressure; Body Weight; Cardiomegaly; Caspase 3; Caspases; Caveolin 3; Endothelin-1; Gene Expression; Heart Rate; Homocysteine; Lipids; Male; Myosin Heavy Chains; Natriuretic Peptide, Brain; Nitric Oxide Synthase Type III; Peptidyl-Dipeptidase A; Physical Conditioning, Animal; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Inbred SHR; Rats, Inbred WKY; RNA, Messenger

We investigated the mechanisms involved in the enhancement of endothelin (ET)-1 vascular reactivity induced by ethanol consumption. Ethanol intake for 2, 6, and 10 weeks enhanced the ET-1-induced contractile response of endothelium-intact but not endothelium-denuded rat carotid rings independently of the treatment duration. Conversely, phenylephrine-induced contraction was not affected by ethanol intake. The contraction induced by IRL1620 [succinyl-(Glu(9),Ala(11,15))-ET-1-(8-21)], a selective ET(B) agonist, was increased after treatment with ethanol in endothelium-intact but not in endothelium-denuded carotid rings. Moreover, ET-1- and IRL1620-induced relaxation was reduced in endothelium-intact phenylephrine-precontracted rings from ethanol-treated rats. Acetylcholine-induced relaxation was not affected by ethanol treatment. N(G)-Nitro-l-arginine methyl ester, 1H-[1,2,4]-oxadiazolo[4,3-a]quinoxalin-1-one, indomethacin, and tetraethylammonium reduced the relaxation induced by IRL1620 in carotid glands from control but not ethanol-treated rats. The mRNA levels for ET(A) and ET(B) receptors were not altered by ethanol consumption. However, ethanol treatment reduced the protein expression of ET(B) receptors. Furthermore, immunohistochemical assays showed reduced immunostaining for endothelial ET(B) receptors after treatment with ethanol. We conclude that ethanol consumption enhances ET-1-induced contraction in the rat carotid and that this response is not different among the three periods of treatment used in this study. Finally, the potentiation of ET-1-induced vascular reactivity is probably caused by reduced expression of relaxing endothelial ET(B) receptors.

Topics: Acetylcholine; Animals; Blood Glucose; Blotting, Western; Body Weight; Carotid Arteries; Central Nervous System Depressants; Dose-Response Relationship, Drug; Endothelin-1; Endothelins; Ethanol; Immunohistochemistry; In Vitro Techniques; Male; Muscle Contraction; Muscle, Smooth, Vascular; Oligopeptides; Peptide Fragments; Peptides, Cyclic; Phenylephrine; Piperidines; Rats; Rats, Wistar; Receptor, Endothelin A; Receptor, Endothelin B; Reverse Transcriptase Polymerase Chain Reaction; Vasoconstrictor Agents; Vasodilator Agents

Obesity is associated with endothelial dysfunction that may contribute to the development of diabetes, hypertension, and atherosclerosis. Endothelin-1 (ET-1), which is produced mostly by vascular endothelial cells, has potent vasoconstrictor and proliferative activity in vascular smooth muscle cells and, therefore, has been implicated in regulation of vascular tonus and the progression of atherosclerosis, suggesting that ET-1 may be important in endothelial dysfunction. We studied whether diet-induced weight loss (i.e., lifestyle modification) affects plasma ET-1 concentration in obese individuals. We measured plasma ET-1 concentration in seven obese men (age: 48 +/- 4 years old, body mass index: 27.7 +/- 0.5 kg/m2) before and after a 3-month, diet-induced weight reduction program (i.e., lifestyle modification program). Caloric restriction reduced body weight from 78 +/- 3 to 68 +/- 2 kg (P < 0.001) and resulted in 12.1 +/- 1.2% reduction in body mass index (24.3 +/- 0.3 kg/m(2), P < 0.0001). After the weight reduction program, systolic and diastolic blood pressure significantly decreased (128 +/- 7 vs. 115 +/- 4 mm Hg, P < 0.05 and 88 +/- 4 vs. 77 +/- 2 mm Hg, P < 0.01, respectively). The plasma level of ET-1 significantly decreased after the program (5.1 +/- 0.4 vs. 4.0 +/- 0.3 pg/ml, P < 0.05). The percentage systolic blood pressure reduction and percentage plasma ET-1 concentration reduction was in a linear relationship (r = 0.86, P < 0.05). Furthermore, the relationship between percentage weight reduction and percentage plasma ET-1 concentration reduction was linear (r = 0.87, P < 0.05). We conclude that weight loss by low-calorie diet (i.e., lifestyle modification) reduces plasma ET-1 concentration in obese individuals. This reduction may contribute to the improvement of obesity-induced endothelial dysfunction.

Topics: Adult; Blood Pressure; Body Mass Index; Body Weight; Endothelin-1; Humans; Life Style; Male; Middle Aged; Obesity; Weight Loss

Male heterozygous Ren-2 transgenic rats and Hannover Sprague-Dawley rats fed a normal or high-salt diet were either untreated or treated with the nonselective receptor ET(A)/ET(B) receptor blocker bosentan or the selective ET(A) receptor blocker, ABT-627, known as atrasentan. Survival rate was partly increased by bosentan and fully normalized by atrasentan. Bosentan did not significantly influence the course of hypertension in TGR, whereas atrasentan significantly decreased BP on both diets. Atrasentan substantially reduced proteinuria, cardiac hypertrophy, glomerulosclerosis and left ventricular ET-1 tissue concentration on both diets. Our data indicate that ET(A) receptor blockade is superior to nonselective blockade in attenuating hypertension, end-organ damage and improving survival rate.

Topics: Animals; Animals, Genetically Modified; Antihypertensive Agents; Atrasentan; Blood Pressure; Body Weight; Bosentan; Cardiomegaly; Disease Models, Animal; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin Receptor Antagonists; Endothelin-1; Glomerulosclerosis, Focal Segmental; Heterozygote; Hypertension; Male; Proteinuria; Pyrrolidines; Rats; Rats, Sprague-Dawley; Receptors, Endothelin; Renin; Sodium Chloride, Dietary; Sulfonamides; Time Factors

Induction of hypercapnia by breathing high concentrations of carbon dioxide (CO(2)) may have beneficial effects on the pulmonary circulation. We tested the hypothesis that exposure to CO(2) would protect against chronic pulmonary hypertension in newborn rats. Atmospheric CO(2) was maintained at <0.5% (normocapnia), 5.5%, or 10% during exposure from birth for 14 days to normoxia (21% O(2)) or moderate hypoxia (13% O(2)). Pulmonary vascular and hemodynamic abnormalities in animals exposed to chronic hypoxia included increased pulmonary arterial resistance, right ventricular hypertrophy and dysfunction, medial thickening of pulmonary resistance arteries, and distal arterial muscularization. Exposure to 10% CO(2) (but not to 5.5% CO(2)) significantly attenuated pulmonary vascular remodeling and increased pulmonary arterial resistance in hypoxia-exposed animals (P < 0.05), whereas both concentrations of CO(2) normalized right ventricular performance. Exposure to 10% CO(2) attenuated increased oxidant stress induced by hypoxia, as quantified by 8-isoprostane content in the lung, and prevented upregulation of endothelin-1, a critical mediator of pulmonary vascular remodeling. We conclude that hypercapnic acidosis has beneficial effects on pulmonary hypertension and vascular remodeling induced by chronic hypoxia, which we speculate derives from antioxidant properties of CO(2) on the lung and consequent modulating effects on the endothelin pathway.

Topics: Animals; Animals, Newborn; Body Weight; Carbon Dioxide; Carboxylic Acids; Chronic Disease; Endothelin Receptor Antagonists; Endothelin-1; Female; Hematocrit; Hypercapnia; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Indans; Oxidative Stress; Oxygen; Pregnancy; Pulmonary Artery; Pulmonary Circulation; Rats; Up-Regulation

In this study, the effects of reduced melatonin concentrations in the long-term period of pinealectomy on mean arterial blood pressure (BP) and vascular responses in isolated rat thoracic aorta were investigated. Rats were pinealectomized (Px) two months before the beginning of the studies. Rings of endothelium-intact and -denuded rat arteries were mounted in isolated tissue baths for the measurements of isometric contractile force. No significant difference was determined between the arterial BP of Px (88.1 +/- 1.9 mmHg) and control (83.8 +/- 1.2 mmHg) rats. All arteries isolated from control and Px rats showed essentially identical contractions in response to phenylephrine, serotonin, calcium, clonidine, vasopressin, and angiotensin-II. Only endothelin-1 (ET-1)-induced contractions in the endothelium-denuded vessels isolated from Px rats were found to be increased to some extent. Pinealectomy did not affect acetylcholine or sodium nitroprusside-induced relaxation in the rat aorta either. These data suggest that reduced melatonin levels two months after pinealectomy did not modify either the vascular reactivity to various vasoconstrictor agents except the partially increased contractile responses to ET-1 in the endothelium-denuded thoracic aortas of Px rats or the endothelium-dependent and -independent relaxations in rat thoracic aorta. Restoration of the increased vascular responses to some vasoconstrictor agents, which were reported previously, may be the reason of why the hypertension is temporary following pinealectomy.

Topics: Acetylcholine; Angiotensin II; Animals; Aorta, Thoracic; Body Weight; Clonidine; Dose-Response Relationship, Drug; Drug Synergism; Endothelin-1; Endothelium, Vascular; Heart; In Vitro Techniques; Male; Organ Size; Phenylephrine; Pineal Gland; Rats; Rats, Wistar; Serotonin; Time Factors; Vasoconstrictor Agents; Vasodilation; Vasopressins

Endothelin (ET)-1 has been implicated in the development of cardiac hypertrophy. We investigated the effect of pravastatin on development of ventricular hypertrophy in spontaneously hypertensive rats (SHR) and whether the attenuated hypertrophic effect was via reduced ET-1 expression. Normolipidemic SHR were treated with one of the following therapies for 8 wk: vehicle, the nonselective ET receptor antagonists bosentan, pravastatin, mevalonate, hydralazine, or combination of pravastatin + mevalonate from the age of 8 wk at the very early stage of cardiac hypertrophy. Treatment with bosentan and pravastatin significantly decreased left ventricular mass index for body weight and cardiomyocyte sizes isolated by enzymatic dissociation. The myocardial ET-1 levels and preproET-1 mRNA assessed using real-time quantitative RT-PCR were significantly higher (both P < 0.001) in the SHR compared with Wistar-Kyoto rats. The increased tissue ET-1 levels can be inhibited after pravastatin administration. Immunohistochemical analysis confirmed the changes of ET-1. Left ventricular mass index for body weight correlated positively with tissue ET-1 levels (P = 0.0004). A dissociation between the effects of blood pressure and cardiac structure was noted, because pravastatin and hydralazine reduced arterial pressure similarly. Pravastatin-induced effects were reversed by the addition of mevalonate. In conclusion, these results suggest a crucial role of cardiac endothelin system in the early development of ventricular hypertrophy in the SHR. Pravastatin is endowed with cardiac antihypertropic properties that are independent of its hemodynamic and hypolipidemic effects and appear to be related to their capacity to decrease cardiac ET-1 levels, which is linked to mevalonate metabolism.

Topics: Animals; Body Weight; Cardiac Pacing, Artificial; Endothelin-1; Hemodynamics; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypertension; Hypertrophy, Left Ventricular; Immunohistochemistry; Male; Myocardium; Organ Size; Pravastatin; Rats; Rats, Inbred SHR; RNA, Messenger; Ventricular Function

The aim of the present study was to evaluate a rat model of placental dysfunction/preeclampsia in pregnancies complicated by maternal diabetes. A second objective was to evaluate the effects of vitamin E treatment in this model.. Normal and streptozotocin-induced diabetic rats of two different strains (U and H) were given intraperitoneal (IP) injections of the angiogenesis inhibitor Suramin (Sigma Chemical Co, St Louis, MO) or saline in early pregnancy, and fed standard or vitamin E-enriched food. The outcome of pregnancy was evaluated on gestational day 20.. In both rat strains Suramin caused fetal growth retardation, decreased placental blood flow, and increased placental concentration of the isoprostane 8-iso-PGF(2alpha). In the U rats Suramin also caused increased fetal resorption rate, increased maternal blood pressure, decreased renal blood flow, and diminished maternal growth. Diabetes caused severe maternal and fetal growth retardation, increased resorption rate, and increased placental 8-iso-PGF(2alpha) concentration independent of Suramin administration. The maternal and fetal effects of Suramin and diabetes were more pronounced in the U strain than in the H strain. Vitamin E treatment improved the status of Suramin-injected diabetic rats: in U rats the blood pressure increase was normalized; and in both U and H rats the decreased placental blood flow was marginally enhanced, and the increase in placental 8-iso-PGF(2alpha) was partly normalized by vitamin E.. Suramin injections to pregnant rats cause a state of placental insufficiency, which in U rats resembles human preeclampsia. The induction of this condition is at least partly mediated by oxidative stress, and antagonized by antioxidative treatment. Maternal diabetes involves increased oxidative stress, and causes both maternal and fetal morbidity, which are only marginally affected by additional Suramin treatment.

Topics: Animals; Antioxidants; Blood Pressure; Body Weight; Diabetes Mellitus, Experimental; Electrolytes; Endothelin-1; Female; Fetal Growth Retardation; Fetal Resorption; Isoprostanes; Lipids; Nitrites; Perfusion; Placenta; Pregnancy; Pregnancy in Diabetics; Pregnancy Outcome; Rats; Rats, Sprague-Dawley; Suramin; Vitamin E

To test the hypothesis that activation of the endothelin type A (ET(A)) receptor contributes to decreased renal excretory function and increased blood pressure in sensory nerve-degenerated rats fed a high-salt diet, neonatal Wistar rats were given vehicle or capsaicin (CAP, 50 mg/kg s.c.) on the first and second day of life. After being weaned, vehicle or CAP-treated rats were fed a normal (NS, 0.5%) or a high- (HS, 4%) sodium diet for 2 wk with or without ABT-627 (5 mg x kg(-1) x day(-1), a selective ET(A) receptor antagonist). Systolic blood pressure increased in CAP-treated rats fed a HS diet (CAP-HS) compared with vehicle-treated rats fed a HS diet (CON-HS, 145 +/- 7 vs. 89 +/- 5 mmHg, P < 0.05). Creatinine clearance and fractional sodium excretion (FE(Na)) decreased in CAP-HS rats compared with CON-HS rats (creatinine clearance, 0.54 +/- 0.05 vs. 0.81 +/- 0.09 ml x min(-1) x 100 g body wt(-1); FE(Na), 8.68 +/- 0.99 vs. 12.53 +/- 1.47%, respectively; P < 0.05). Water and sodium balance increased in CAP-HS rats compared with CON-HS (water balance, 20.2 +/- 1.5 vs. 15.5 +/- 1.9 ml/day; sodium balance, 11.9 +/- 3.1 vs. 2.4 +/- 0.3 meq/day, respectively; P < 0.05). The endothelin (ET)-1 levels in plasma and isolated glomeruli increased by about twofold in CAP-HS rats compared with CON-HS rats (P < 0.05). ABT-627 prevented the decrease in creatinine clearance and FE(Na), the increase in water and sodium balance, and the increase in blood pressure in CAP-HS rats (P < 0.05). Therefore, the blockade of the ET(A) receptor ameliorates the impairment of renal excretory function and prevents the elevation in blood pressure in salt-sensitive hypertension induced by degeneration of sensory nerves, indicating that the activation of the ET(A) receptor impairs renal function and contributes to the development of a salt-induced increase in blood pressure in this model.

Topics: Animals; Blood Pressure; Body Weight; Capsaicin; Creatinine; Diet; Eating; Endothelin A Receptor Antagonists; Endothelin-1; Female; Hypertension; Kidney Diseases; Kidney Glomerulus; Pregnancy; Radioimmunoassay; Rats; Rats, Wistar; Sensory Deprivation; Sodium, Dietary; Water-Electrolyte Balance

We have recently found that nonselective endothelin ETA/ETB receptor blockade markedly improves survival rate and ameliorates end-organ damage in male homozygous rats transgenic (TGR) for the mouse Ren-2 renin gene without lowering blood pressure. Because activation of the ETA receptor may be responsible for the detrimental effects of ET in the development of hypertension, this study was performed to determine whether ETA or ETA/ETB receptor blockade exerts these beneficial effects. TGR and age-matched normotensive Hannover Sprague-Dawley rats fed a high-salt diet received either vehicle or bosentan and atrasentan (ABT-627) as nonselective ETA/ETB and selective ETA receptor blockers, respectively, from 29 until 90 days of age. The survival rate of 48% in untreated TGR was significantly (P<0.01) improved to 79% by bosentan and to 92% by ABT-627 (ABT-627 versus bosentan P<0.05). Proteinuria, glomerulosclerosis, and cardiac hypertrophy, as well as ET-1 content in left ventricular tissue, were significantly reduced by bosentan and to a greater degree by ABT-627, which also significantly attenuated the rise in blood pressure (P<0.05). Our data indicate that the ET system, especially via ETA receptors, plays an important role in the development of hypertensive end-organ damage and confirm the concept that the predominant role of ETB receptors within the peripheral vasculature is to mediate the vasorelaxant actions of ET-1. They also demonstrate that selective blockade of ETA receptors is superior to nonselective ETA/ETB in attenuating hypertension, hypertensive organ damage, and survival rate.

Topics: Animals; Animals, Genetically Modified; Atrasentan; Blood Pressure; Body Weight; Bosentan; Cardiomegaly; Endothelin A Receptor Antagonists; Endothelin-1; Glomerulosclerosis, Focal Segmental; Heart Ventricles; Hypertension; Kidney; Male; Myocardium; Organ Size; Osmolar Concentration; Proteinuria; Pyrrolidines; Rats; Rats, Sprague-Dawley; Renin; Sodium Chloride, Dietary; Sulfonamides; Survival Analysis

Male gender is a risk factor for progression of autosomal-dominant polycystic kidney disease (ADPKD), clinically and in the Han:SPRD rat model. Orchiectomy limits progression, but mechanisms of the detrimental effect of androgen, and/or beneficial effects of estrogen, are not known. This protocol tested the hypothesis that male gender (intact androgen status) promotes progression, while female gender (intact estrogen status) is protective; and that these disease-modifying effects are due to changes in expression of known fibrotic mediators.. Studies were performed in male and female noncystic control (+/+) and cystic (+/-) rats subjected to orchiectomy, ovariectomy, or sham operation. At 12 weeks of age, renal function was measured. Blood and kidneys were taken for measurement of plasma and renal renin, endothelin (ET-1), endothelial nitric oxide synthase (eNOS), and vascular endothelial growth factor (VEGF), using biochemical, protein expression, and immunohistochemical methods.. Cystic male rats exhibited significantly reduced glomerular filtration (GFR) and effective renal plasma flow (ERPF) rates, with suppression of plasma and renal renin, up-regulation of renal ET-1 and eNOS, and down-regulation of renal VEGF expression. Orchiectomy attenuated the fall in GFR and ERPF, while numerically limiting changes in eNOS and VEGF. Female rats exhibited less cystic growth, with normal renin status, lesser elevation of renal ET-1, and proportionately lesser changes in VEGF and eNOS. Ovariectomy led to higher blood pressure and reduced GFR and ERPF, with a trend toward upregulation of ET-1, and significant down-regulation of VEGF and eNOS.. Female gender is protective, but ovariectomy attenuates the protective effect of female gender, in association with changes in renal expression of ET-1, VEGF, and eNOS. The accelerated disease in male rats can be attenuated by orchiectomy and consequent changes in expression of disease mediators.

Topics: Androgens; Animals; Body Weight; Endothelin-1; Estrogens; Female; Fibrosis; Kidney; Male; Nitric Oxide; Nitric Oxide Synthase Type III; Orchiectomy; Organ Size; Ovariectomy; Polycystic Kidney, Autosomal Dominant; Rats; Rats, Mutant Strains; Rats, Sprague-Dawley; Renin-Angiotensin System; Vascular Endothelial Growth Factor A

In vivo studies have shown that chronic alcohol consumption sensitizes the liver to endotoxemic shock, leading to liver microcirculation disruption. In the present study, we investigated the molecular mechanisms involved, focusing on endothelial nitric oxide synthase (eNOS) activity and regulation, which represents one of the major vasodilatory pathways. Male Sprague-Dawley rats were fed an alcohol liquid diet or a control isocaloric diet for 5 weeks. Priming effects of ethanol were studied in a model with or without a 24-h LPS treatment (1 mg/kg body weight). At the end of the diet, liver tissue was harvested for western blot, reverse transcriptase-PCR, histological analysis, and immunostaining and blood for serum alanine aminotransferase analysis. Chronic ethanol and LPS alone induced a mild hepatitis and infiltration, respectively. Combined, LPS and chronic ethanol feeding showed a synergistic effect on the liver, leading to extensive steatohepatitis with extensive focal necrosis associated with significantly higher levels of serum ALT. Chronic ethanol and LPS significantly inhibited eNOS activity, but exerted their effects through different mechanisms. Caveolin-1, an eNOS inhibitory protein, was upregulated after LPS and chronic alcohol consumption. Additionally, chronic alcohol consumption down-regulated endothelin B receptor, eNOS protein levels, and eNOS phosphorylation. In conclusion, chronic ethanol consumption and LPS share a similar pathophysiology and both lead to the impairment of eNOS activity, but through distinct molecular mechanisms. The presence of focal necrosis in a mild stress model could provide a good animal study to investigate the advanced stages of alcoholic liver diseases.

Topics: Alanine Transaminase; Alcohol Drinking; Animals; Blotting, Western; Body Weight; Down-Regulation; Drug Synergism; Endothelin-1; Endotoxins; Ethanol; Gene Expression Regulation, Enzymologic; Hepatitis; Immunohistochemistry; Lipopolysaccharides; Liver; Male; Necrosis; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Phosphorylation; Rats; Rats, Sprague-Dawley; Receptor, Endothelin B; Reverse Transcriptase Polymerase Chain Reaction; RNA; RNA, Messenger

In the present study, we investigated the effects of long-term treatment with the endothelin (ET) antagonist atrasentan, an ET(A)-selective antagonist, on whole body glucose metabolism and insulin signaling in a commonly used model of insulin resistance, the Zucker fatty rat. Zucker lean and fatty rats were maintained for 6 weeks on either control or atrasentan-treated water. Euglycemic-hyperinsulinemic clamps (4 mU/kg per minute) were performed at the end of the 6-week treatment on a subset of rats (n=10/treatment). In another subset (n=5/treatment), an insulin tolerance test was performed; liver and muscle tissues were harvested 10 minutes following the challenge for further analysis. Results of the clamps demonstrated that long-term atrasentan treatment significantly increased whole body glucose metabolism in fatty rats compared with vehicle control subjects. Insulin-induced insulin receptor substrate 1 tyrosine and protein kinase B serine phosphorylation were significantly reduced in the liver and muscle of fatty animals compared with their lean littermates. This reduction was overcome with atrasentan treatment in the liver but not in the muscle. There was no difference between lean and fatty animals, however, in insulin receptor substrate 1 and protein kinase B protein expression in the liver and muscle and no effect by atrasentan. In contrast, expression of the regulatory subunit of PI-3 kinase (p85alpha) was significantly increased in the liver but not in the muscle of fatty animals compared with their lean littermates and this was normalized to levels of lean animals with atrasentan treatment. These findings indicate that long-standing ET antagonism improves whole body glucose metabolism in Zucker fatty rats through improvements in insulin signaling in the liver. These results indicate that therapeutic ET antagonism may assist in correcting the insulin-resistant state.

Topics: Animals; Atrasentan; Blood Pressure; Body Weight; Drinking; Endothelin-1; Glucose; Glucose Clamp Technique; Insulin; Insulin Resistance; Liver; Muscle, Skeletal; Obesity; Pyrrolidines; Rats; Rats, Zucker; Signal Transduction

The diabetic heart shows increased fibrosis, which impairs cardiac function. Endothelin (ET)-1 and nuclear factor-kappaB (NF-kappaB) interactively regulate fibroblast growth. We have recently demonstrated that Punica granatum flower (PGF), a Unani anti-diabetic medicine, is a dual activator of peroxisome proliferator-activated receptor (PPAR)-alpha and -gamma, and improves hyperglycemia, hyperlipidemia, and fatty heart in Zucker diabetic fatty (ZDF) rat, a genetic animal model of type 2 diabetes and obesity. Here, we demonstrated that six-week treatment with PGF extract (500 mg/kg, p.o.) in Zucker diabetic fatty rats reduced the ratios of van Gieson-stained interstitial collagen deposit area to total left ventricular area and perivascular collagen deposit areas to coronary artery media area in the heart. This was accompanied by suppression of overexpressed cardiac fibronectin and collagen I and III mRNAs. Punica granatum flower extract reduced the up-regulated cardiac mRNA expression of ET-1, ETA, inhibitor-kappaBbeta and c-jun, and normalized the down-regulated mRNA expression of inhibitor-kappaBalpha in Zucker diabetic fatty rats. In vitro, Punica granatum flower extract and its components oleanolic acid, ursolic acid, and gallic acid inhibited lipopolysaccharide-induced NF-kappaB activation in macrophages. Our findings indicate that Punica granatum flower extract diminishes cardiac fibrosis in Zucker diabetic fatty rats, at least in part, by modulating cardiac ET-1 and NF-kappaB signaling.

Topics: Animals; Body Weight; Cell Line; Diabetes Mellitus, Type 2; Endothelin-1; Fibrosis; Flowers; Gene Expression Profiling; Gene Expression Regulation; Heart; Lythraceae; Male; Mice; Myocardium; NF-kappa B; Obesity; Organ Size; Plant Extracts; Rats; Rats, Zucker

Intimal thickening, due to smooth muscle cell migration and proliferation, is considered to be one of the major components of vascular proliferative disorders such as atherosclerosis and restenosis. One experimental model, resulting in intimal thickening in the rabbit, involves placing a silicon collar around the carotid artery, and is used in this study. Endothelin is known to act as a strong mitogen and to stimulate smooth muscle cell proliferation and migration. We investigated the contribution of endothelin to the development of collar-induced intimal thickening and the effects of TAK-044, (5 mg kg(-1) daily, s.c.), a non-selective ET(A)/ET(B) receptor antagonist, on intimal thickening and vascular reactivity changes in the collared rabbit carotid artery. Endothelin levels and the intimal cross-sectional area, as well as the ratio of intimal area to media (index), increased significantly in collared arteries as compared with those in sham-operated arteries. TAK-044 significantly inhibited intimal thickening and also decreased the index without affecting increased endothelin levels in collared arteries. Vascular reactivity changes in response to collaring produced predictable effects, such as decreased contractile responses to vasoconstrictor agents and increased sensitivity to serotonin (5-hydroxytryptamine, 5-HT). In terms of contractile responses in this model, TAK-044, in particular, did not affect collar-induced vascular reactivity changes. These results suggest that endothelin may be involved in the pathogenesis of collar-induced intimal thickening. As an endothelin receptor antagonist, TAK-044 may potentially be beneficial in the treatment of atherosclerosis.

Topics: Animals; Blood Pressure; Blood Vessels; Body Weight; Endothelin-1; Female; Immunohistochemistry; Ki-67 Antigen; Male; Rabbits; Receptors, Endothelin; Tunica Intima

1. The purpose of this study was to investigate whether a membrane-permeable superoxide dismutase mimetic, tempol, added either alone or in combination with the nitric oxide (NO) donor molsidomine, prevents the development of pulmonary hypertension (PH) in chronic hypoxic rats. 2. Chronic hypobaric hypoxia (10% oxygen) for 2 weeks increased the right ventricular systolic pressure (RVSP), right ventricle and lung wet weight. Relaxations evoked by acetylcholine (ACh) and the molsidomine metabolite SIN-1 were impaired in isolated proximal, but not distal pulmonary arteries, from chronic hypoxic rats. 3. Treatment with tempol (86 mg x kg(-1) day(-1) in drinking water) normalized RVSP and reduced right ventricular hypertrophy, while systemic blood pressure, lung and liver weights, and blunted ACh relaxation of pulmonary arteries were unchanged. 4. Treatment with molsidomine (15 mg x kg(-1) day(-1) in drinking water) had the same effects as tempol, except that liver weight was reduced, and potassium and U46619-evoked vasoconstrictions in pulmonary arteries were increased. Combining tempol and molsidomine did not have additional effects compared to tempol alone. ACh relaxation in pulmonary arteries was not normalized by these treatments. 5. The media to lumen diameter ratio of the pulmonary arteries was greater for the hypoxic rats compared to the normoxic rats, and was not reversed by treatment with tempol, molsidomine, or the combination of tempol and molsidomine. 6. We conclude that tempol, like molsidomine, is able to correct RVSP and reduce right ventricular weight in the rat hypoxic model. Functional and structural properties of pulmonary small arteries were little affected. The results support the possibility that superoxide dismutase mimetics may be a useful means for the treatment of PH.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Administration, Oral; Animals; Body Weight; Chronic Disease; Cyclic N-Oxides; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Synergism; Drug Therapy, Combination; Endothelin-1; Free Radical Scavengers; Heart Rate; Hypertrophy, Right Ventricular; Hypoxia; Male; Molsidomine; Muscle, Smooth, Vascular; Organ Size; Pulmonary Artery; Rats; Rats, Wistar; Spin Labels; Superoxide Dismutase; Vasoconstriction; Vasodilation; Ventricular Pressure

1. Peroxisome proliferator activated receptor gamma (PPARgamma) has been implicated in several cellular pathways assumed to beneficially affect heart failure progression. In contrast, population-based studies demonstrate an increased incidence of heart failure in patients treated with PPARgamma agonists. Therefore, we examined the effect of pioglitazone, a PPARgamma agonist, on chronic left ventricular remodeling after experimental myocardial infarction (MI) in mice. 2. Mice were treated with placebo or pioglitazone (20 mg x kg(-1) by gavage) from week 1 to week 6 after ligation of the left anterior descending artery. Serial transthoracic echocardiography was performed at weeks 1, 3, and 6. 3. Over 6 weeks, there was no difference in mortality (placebo 12%, pioglitazone 10%). Echocardiography showed significant left ventricular dilatation in animals with MI (week 6, end-systolic area, placebo sham 9.6+/-1.3 vs placebo MI 14.4+/-2.5 mm(2)). However, there was no difference between the placebo and pioglitazone groups (week 6, end-systolic area, pioglitazone MI 14.8+/-2.9 mm(2), P=NS vs placebo). 4. Moreover, there were no changes in metabolic parameters, inflammation, and collagen deposition. Endothelial function in the aorta was not changed by PPARgamma activation. 5. In conclusion, PPARgamma activation did not adversely affect left ventricular remodeling and survival in mice with chronic MI. However, we were also not able to identify a protective effect of pioglitazone.

Topics: Animals; Aorta; Blood Glucose; Body Weight; Chronic Disease; Collagen; Coronary Vessels; Cytokines; Disease Models, Animal; Drug Evaluation, Preclinical; Echocardiography; Endothelin-1; Endothelium, Vascular; Inflammation Mediators; Intubation, Gastrointestinal; Male; Mice; Mice, Inbred C57BL; Myocardial Infarction; Myocardium; Organ Size; Phenylephrine; Pioglitazone; Thiazolidinediones; Triglycerides; Vasoconstriction; Ventricular Dysfunction, Left; Ventricular Remodeling

Vascular endothelial cells produce endothelin (ET)-1, a potent vasoconstrictor peptide, and nitric oxide (NO), a potent vasodilator substance. There are interactions between ET-1 and NO. Exercise results in a marked decrease in renal blood flow. We previously reported that exercise causes an increase of ET-1 production in the kidney, whereas production of NO in the kidney is decreased. Furthermore, we recently revealed that the magnitude of decrease in blood flow to the kidney during exercise was significantly attenuated by the administration of the endothelin-A (ET(A)) receptor antagonist, strongly suggesting that endogenously increased ET-1 participates in the decrease of blood flow in the kidney during exercise. Because it was demonstrated that ET-1 depresses NO synthase (NOS) activity of cultured cells in vitro, we hypothesized that an increase of ET-1 production in kidney during exercise contributes to a decrease of NO production in kidney in vivo. We studied whether administration of the ET(A) receptor antagonist attenuates the decreases of NOS activity and NO production in the kidney during exercise. Rats performed treadmill running for 30 min after pretreatment with an ET(A) receptor antagonist (TA-0201, 0.5 mg/kg; TA-0201-treated exercise group) or vehicle (vehicle-treated exercise group). Control rats remained at rest (vehicle-treated sedentary group). Blood flow in the kidney was decreased by this exercise, but the magnitude of the decrease after pretreatment with TA-0201 was significantly smaller than that after pretreatment with vehicle. NOS activity in kidney was significantly lower in the vehicle-treated exercise group than in the vehicle-treated sedentary group, whereas that in the TA-0201-treated exercise group was significantly higher than that in the vehicle-treated exercise group. Expressions of endothelial NOS protein and NOx, the stable end product of NO, i.e., nitrite/nitrate, concentration in the kidney were significantly lower in the vehicle-treated exercise group than in the vehicle-treated sedentary group, whereas those in the TA-0201-treated exercise group were significantly higher than those in the vehicle-treated exercise group. The data suggest that increased ET-1 production in the kidney during exercise contributes to the decreases of NOS activity and NO production. Therefore, the present study provides a possibility that the exercise-induced increase in production of ET-1 in the kidney causes a decrease in blood flow in th

Topics: Animals; Body Weight; Endothelin A Receptor Antagonists; Endothelin Receptor Antagonists; Endothelin-1; Enzyme Inhibitors; Kidney; Male; Nephrectomy; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Organ Size; Physical Exertion; Pyrimidines; Rats; Rats, Wistar; Receptor Cross-Talk; Sulfonamides

Endothelial dysfunction has been suggested to play an important role in the development of obesity-induced hypertension. Because endothelin release increases in response to endothelial damage, we examined whether endothelin-1 contributes to increased arterial pressure in a model of visceral obesity produced by feeding Sprague-Dawley rats a high-fat (HF) diet (40% fat w/w, n=6) for 12 months. Arterial and venous catheters were implanted for measurement of mean arterial pressure (MAP) and heart rate (HR) 24 hours per day and intravenous infusions. After a 5-day control period, rats were infused with the selective endothelin-1 type A receptor (ET-A) blocker ABT-627 (2.5 mg/kg per day, IV) for 9 days, followed by a recovery period. Rats fed a standard chow (normal fat, or NF, group: n=6) for 12 months were also infused with ET-A blocker and were used as controls. Compared with NF rats, HF rats had higher MAP (113+/-4 versus 98+/-2 mm Hg), increased visceral fat (18.7+/-2.0 versus 10.8+/-1.4 g), and 3.2-fold increase in plasma leptin despite similar total body weight gain. Long-term ET-A blockade markedly reduced MAP in HF (-14+/-3 mm Hg) and NF (-14+/-2 mm Hg), but it had no effect on HR, GFR, or PRA. These results indicate that a long-term HF diet may cause visceral obesity and increased MAP, even in the absence of major changes in total body weight. Endothelin-1 appears to play an important role in the maintenance of arterial pressure in rats fed HF and NF diets, but it does not appear to contribute to increased MAP in this model of diet-induced hypertension.

Topics: Adipose Tissue; Animals; Atrasentan; Blood Pressure; Body Weight; Eating; Endothelin A Receptor Antagonists; Endothelin-1; Fats; Heart Rate; Hormones; Hypertension; Kidney; Male; Obesity; Pyrrolidines; Rats; Rats, Sprague-Dawley; Viscera

There is little information whether cardiac capillary supply is deranged in diabetes. Hyperglycaemia is a potent stimulus for endothelin-1 (ET-1) production. We therefore hypothesised that increased ET-1 production in Streptozotocin-induced Type 1 diabetes causes abnormalities of cardiac capillaries and the aorta. To this end we compared the effects of an ET receptor A blocker (ETA-RB) with that of an ACE-inhibitor (ACE-i) or their combination in rats with Streptozotocin (STZ) diabetes.. Sprague Dawley rats were injected with 65 mg STZ i.v. and subsequently developed diabetes. Rats were left untreated or received daily either the ACE-i Trandolapril, the ETA-RB Darusentan or a combination of both. After 6 months the experiment was terminated and the heart and the aorta were investigated using quantitative morphological techniques.. ACE-i but not ETA-RB lowered blood pressure in STZ Type 1 diabetic rats. Capillary length density was lower in untreated STZ diabetic rats (2932+/-128 mm/mm3) compared to non-diabetic control rats (3410+/-252 mm/mm3). Treatment with ACE-i (3568+/-431 mm/mm3), but not with ETA-RB (2893+/-192 mm/mm3), prevented the decrease in capillary supply. Volume density of the myocardial interstitium was higher in untreated STZ diabetic rats (0.86+/-0.04%) compared to non-diabetic control rats (0.36+/-0.06%). In all three intervention groups the values were lower (ACE-i: 0.53+/-0.05%, ETA-RB: 0.7+/-0.08% and combination: 0.69+/-0.1).. Our study identifies a capillary defect of the heart in STZ diabetes, i.e. decreased capillary supply. This abnormality was reversed by ACE-i, but not by ETA-R blockade. A similar trend, although not complete normalisation, was seen in cardiac fibrosis.

Topics: Albuminuria; Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta, Thoracic; Arterioles; Blood Glucose; Blood Pressure; Body Weight; Cardiovascular Diseases; Collagen Type IV; Coronary Vessels; Diabetes Mellitus, Experimental; Endothelin A Receptor Antagonists; Endothelin-1; Fibrosis; Gene Expression; Heart; Immunohistochemistry; In Situ Hybridization; Indoles; Male; Myocardium; Phenylpropionates; Pyrimidines; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Transforming Growth Factor beta

The elevation of plasma L-arginine levels stimulates nitric oxide (NO) synthesis, but the underlying mechanisms are not yet understood. We examined the role of physiological changes in pulmonary arteries on endogenous NO production. Male Wistar rats were divided into following groups: (1) control rats receiving normal water orally, (2) ARG rats receiving L-arginine water orally, (3) MCT rats injected with monocrotaline (MCT) on day 0 and receiving normal water orally, and (4) MCT+ARG rats injected with MCT on day 0 and receiving L-arginine water orally. The rats were studied after 23 days of dietary intervention. In MCT+ARG rats, supplemental L-arginine exhibited a significant pulmonary vasodilatory effect, as shown by a decreased pulmonary arterial pressure (PAP) (P<0.001), decreased right ventricular hypertrophy (P<0.01), and improved endothelium-dependent relaxation (P<0.01). Also L-arginine inhibited the elevation of plasma endothelin-1 (P<0.01). Oral L-arginine administration increased plasma L-arginine levels about twofold, but in only MCT+ARG rats (i.e., not in ARG rats) did the urinary nitrate excretion significantly increase (P<0.05), which is an indicator of endogenous NO formation. Oral administration of L-arginine is effective against pulmonary vascular remodeling. The data also suggest that the initial elevation of PAP is important for the induction of endogenous NO synthesis.

Topics: Animals; Arginine; Blood Pressure; Body Weight; Endothelin-1; Endothelium, Vascular; Hypertension, Pulmonary; Male; Nitrates; Nitric Oxide; Pulmonary Artery; Rats; Rats, Wistar

Daily administration of prednisolone, but not the derivative NCX-1015 (or prednisolone 21-[4'-nitrooxymethyl]benzoate), to rats resulted in a time- and dose-dependent increase in mean arterial blood pressure (MABP), significant after 1 week for the dose of 6.9 micromol/kg i.p. (n = 10; P < 0.05), and 3 weeks for the lower dose of 1.38 micromol/kg. A similar dichotomy of behavior was observed with respect to myocardial contractility and renal vascular resistance, in either case augmented by 3-week treatment with prednisolone but not NCX-1015. In contrast, both NCX-1015 and prednisolone reduced plasma levels of corticosterone in a dose- (dose range of 0.69-6.9 micromol/kg i.p.) and time-dependent (1-3 weeks) manner. Similar profiles were obtained for plasma nitrate values, although they were increased selectively after NCX-1015 administration. In contrast, prednisolone, but not NCX-1015, augmented plasma endothelin 1 (ET-1) with a profile that mirrored the changes observed in MABP and renal blood flow. Supply in the drinking water of the ET-1 receptor type A (ETA) antagonist FR139317 [(R-2-[(R)-2-[(S)-2-[[1-(hexahydro-1H-azepinyl)]-carbonyl]amino-4-methylpentanoyl]-amino-3-(2-pyridil)propionic] or mixed ETA/B, but not of selective ETB, antagonists prevented the changes produced by a 21-day treatment with prednisolone. In conclusion, this study indicates 1) a lack of occurrence of cardiovascular alterations by nitro-releasing derivative of prednisolone (NCX-1015), and 2) a functional link between prednisolone effects and the endogenous endothelin-1 system.

Topics: Animals; Anti-Inflammatory Agents; Azepines; Blood Pressure; Body Weight; Cardiovascular System; Endothelin Receptor Antagonists; Endothelin-1; Heart Rate; Indoles; Kidney; Plasma; Prednisolone; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Vascular Resistance

Under normoxic conditions in vitro, isolated pulmonary arteries from broilers exhibit reduced endothelium-dependent relaxation responses when compared with Leghorns. In vivo, hypoxia increases the susceptibility of broiler chickens to pulmonary hypertension syndrome (PHS), whereas Leghorns are considered resistant to PHS. Because L-arginine supplementation decreases the incidence of PHS in vivo and improves the relaxation responses of broiler isolated pulmonary arteries in vitro, we hypothesized that in vitro hypoxia would further reduce the relaxation responses of broilers to endothelium-derived nitric oxide (EDNO)-dependent vasodilators and that L-arginine supplementation would alleviate this impairment. As a test of this hypothesis, pulmonary arteries from broiler and Leghorn chickens were isolated and exposed to normoxia or hypoxia in the presence or absence of L-arginine while their constriction and relaxation responses to vasoactive compounds were recorded. In broilers, hypoxia did not affect the constriction responses of isolated pulmonary arteries but decreased EDNO-dependent acetylcholine-induced relaxation responses. In contrast, in Leghorns hypoxia increased endothelin-1-induced vasoconstriction responses and reduced the EDNO-dependent relaxation responses only to the lowest concentration of acetylcholine used. L-Arginine supplementation augmented the relaxation responses to acetylcholine in broilers and Leghorns under normoxia but failed to augment them under hypoxia. Relaxation responses to the NO donor, sodium nitroprusside, were not affected by hypoxia in Leghorns but were increased by hypoxia in broilers. These results suggest that the increased incidence of PHS in broiler chickens reared under hypoxia may be associated with a hypoxia-induced reduction in the synthesis or activity of EDNO in the pulmonary circulation.

Topics: Acetylcholine; Animals; Arginine; Body Weight; Chickens; Endothelin-1; Endothelium, Vascular; Heart Ventricles; Hypertension, Pulmonary; Hypoxia; Muscle Contraction; Muscle Relaxation; Muscle, Smooth, Vascular; Nitric Oxide; Nitric Oxide Donors; Nitroprusside; Organ Size; Oxygen; Potassium Chloride; Poultry Diseases; Pulmonary Artery

To probe into therapeutic effect and its mechanism of "Huo Xue Bu Qi Fang" (HXBQF) on fetal rats with intrauterine growth retardation (IUGR).. The model of pregnant rat with IUGR was established by passive smoking method. Forty pregnant rats with IUGR were randomly divided into intervention group (with high-, middle- and low-dose Chinese traditional medicine) and non-intervention group. In addition, 10 normal pregnant rats were taken into control group. Intervention group was adminstered with 16.2, 5.4 and 1.62 g/kg HXBQF respectively. Non-intervention group and control group were administered with 10 ml/kg saline. Fetal rats were taken out, and blood and urine samples were collected from pregnant rats on day 21 of the pregnancy. The weight, nose-hip-length and poundera index of these fetal rats were measured. Serum NO, plasma ET-1 and urine 8-epi-PGF2 alpha level from pregnant rats were determined by nitro-reductase method, radioimmunoassay (RIA) and enzyme immunoassay (EIA) respectively.. Compared with fetal rats from non-intervention group, fetal weight, distance between nose-hip, poundera index serum NO level and NO/ET-1 were increased, plasma ET-1 level and urine 8-epi-PGF2 alpha level were decreased in those from intervention group (P < 0.01).. There is an enhancement of lipid peroxidation and NO/ET-1 ratio imbalance in pregnant rats with IUGR. HXBQF has good therapeutic effect on IUGR since it can inhibit lipid oxidation and regulate NO/ET-1 balance.

Topics: Animals; Antioxidants; Body Weight; Dinoprost; Drugs, Chinese Herbal; Endothelin-1; Female; Fetal Growth Retardation; Nitric Oxide; Pregnancy; Random Allocation; Rats; Rats, Sprague-Dawley

BACKGROUND.: Transplant arteriosclerosis is one of the main features of chronic graft failure in organ transplantation. In this article, the authors investigate mechanisms of mycophenolate mofetil (MMF) on prevention of transplant arteriosclerosis in a rat aortic allograft model.. Orthotopic rat abdominal aortic transplantation was performed from Brown Norway (RT1) to Lewis (RT1) rats. The recipients were divided into three oral treatment groups: (1). vehicle; (2). MMF40 (40 mg/kg); and (3). MMF20 (20 mg/kg). The authors histologically and immunohistochemically evaluated neointima formation; infiltration of macrophages and T cells; and expression of endothelin (ET)-1, platelet-derived growth factor (PDGF)-B, PDGF receptor-beta (Rbeta), transforming growth factor (TGF) beta 1, and osteopontin (OPN). Using cultured rat vascular smooth muscle cells (VSMC), effects of mycophenolic acid (MPA) on ET-1-induced proliferation and ERK1/2 activation were also examined in vitro.. In the vehicle group, marked neointima formation was observed, with massive macrophages and T-cell infiltration in neointima, media, and adventitia. Marked expression of ET-1, PDGF-B, PDGFR-beta, TGFbeta1, and OPN were also observed in neointima. In the MMF40 and MMF20 groups, neointima formation was halted, but macrophages and T cells were infiltrated in the adventitia and adhered to the endothelium. In the MMF40 group, medial infiltration by macrophages and T cells and intimal expression of ET-1, PDGF-B, PDGFR-beta, TGFbeta1, and OPN was inhibited compared with the vehicle and MMF20 groups. Furthermore, MPA inhibited ET-1-induced VSMC proliferation but failed to inhibit its ERK1/2 activation.. MMF treatment might have preventive potential in transplant patients with chronic vasculopathy through inhibition of VSMC proliferation.

Topics: Animals; Aorta, Abdominal; Aortic Diseases; Arteriosclerosis; Body Weight; Cell Division; Cells, Cultured; Endothelin-1; Growth Substances; Immunosuppressive Agents; Macrophages; Male; Muscle, Smooth, Vascular; Mycophenolic Acid; Myocytes, Smooth Muscle; Rats; Rats, Inbred BN; Rats, Inbred Lew; Rats, Sprague-Dawley; T-Lymphocytes; Tunica Intima

To evaluate the role of endothelin-1 (ET-1) in hypertension, we investigated density and distribution of ETA and ETB receptors in hearts and kidneys of deoxycorticosterone acetate (DOCA)-salt and 1 kidney -- 1 clip (1K1C) hypertensive rats.. Five groups of uninephrectomized Wistar rats were put on a low salt diet. Three groups of rats drank tap water and two groups received saline. One group of each regimen received DOCA subcutaneously and two corresponding groups without DOCA served as controls. The fifth group of rats had the renal artery clipped to induce 1K1C hypertension. At 6 weeks, mean arterial pressure (MAP) was recorded and membrane binding assays using 125I-ET-1 were carried out.. MAP was increased from control 122 +/- 3 to 155 +/- 6 and 218 +/- 11 mmHg in DOCA-salt and 1K1C rats, respectively, and cardiac weight index was increased. ETA receptors were predominantly expressed in the heart, whereas ETB receptors were predominant in the kidney. In the kidneys, the density of the ETB receptor subtype was upregulated in DOCA-salt and 1K1C rats from 160 +/- 8 to 217 +/- 12 and 190 +/- 2 fmol/mg (P < 0.05), respectively, and ETA tended to be downregulated (P = 0.057). Plasma renin activity was decreased in DOCA-salt rats from 17 +/- 3 to 0.17 +/- 0.01 ng/ml per h and increased in 1K1C rats on low salt diet to 30 +/- 5 ng/ml per h.. Since ETB is the predominant endothelin receptor in the kidneys, upregulation of the ETB receptor mediating vasodilation and downregulation of the ETA receptor mediating vasoconstriction would be compatible with a mainly renal counter-regulatory effect of endothelin-1 to hypertension. Both low and high renin models of hypertension may be affected.

Topics: Animals; Blood Pressure; Body Weight; Desoxycorticosterone; Endothelin-1; Heart Rate; Hypertension, Renal; Iodine Radioisotopes; Kidney; Myocardium; Radioligand Assay; Rats; Rats, Wistar; Receptor, Endothelin A; Receptor, Endothelin B; Renin; Sodium Chloride; Up-Regulation

Endothelin-1 (ET-1) is a 21-amino-acid peptide, derived from vascular endothelial cells, with potent vasoconstrictor activity. ET-1 has been implicated in diverse physiological or pathological processes, including the vascular changes associated with sepsis. However, the factors that regulate ET-1-associated toxicity during bacterial infections, or in other settings, are not fully understood. Both the pathology associated with certain allergic and autoimmune disorders, and optimal host defence against bacterial and parasitic infections are mediated by mast cells. In vitro, mast cells can produce ET-1 (ref. 11), undergo ET-1-dependent and endothelin-A receptor (ET(A))-dependent activation, and release proteases that degrade ET-1 (ref. 14). Although the potential relationships between mast cells and the ET-1 system thus may be complex, the importance of interactions between ET-1 and mast cells in vivo is obscure. Here we show that ET(A)-dependent mast-cell activation can diminish both ET-1 levels and ET-1-induced pathology in vivo, and also can contribute to optimal survival during acute bacterial peritonitis. These findings identify a new biological function for mast cells: promotion of homeostasis by limiting the toxicity associated with an endogenous mediator.

Topics: Animals; Body Temperature; Body Weight; Cell Degranulation; Cell Survival; Chymases; Diarrhea; Drug-Related Side Effects and Adverse Reactions; Egtazic Acid; Endothelin-1; Female; Homeostasis; Injections, Intraperitoneal; Mast Cells; Mice; Mice, Inbred C57BL; Mice, Knockout; Mutation; Oligopeptides; Peptides, Cyclic; Peritonitis; Proto-Oncogene Proteins c-kit; Serine Endopeptidases; Stem Cells; Survival Rate

Peroxisome proliferator-activated receptors (PPARs) may modulate in vitro the vascular production of vasoactive peptides such as endothelin-1 (ET-1). Thus, we investigated in vivo the interaction between PPARs and ET-1 in deoxycorticosterone acetate (DOCA)-salt rats that overexpress vascular ET-1.. Unilaterally nephrectomized 16-week-old Sprague-Dawley rats (Uni-Nx) were divided into 4 groups (n=6 each): control group, DOCA-salt group, DOCA-salt+PPAR-gamma activator (rosiglitazone, 5 mg x kg(-1) x d(-1)), or DOCA-salt+PPAR-alpha activator (fenofibrate, 100 mg x kg(-1) x d(-1)). Systolic blood pressure was significantly increased in the DOCA-salt group (240+/-11 vs 121+/-2 mm Hg in Uni-Nx, P<0.01). Progression of hypertension was partially prevented by coadministration of rosiglitazone (172+/-3 mm Hg vs DOCA-salt, P<0.05) but not by fenofibrate. Both PPAR activators abrogated the increase in prepro-ET-1 mRNA content in the mesenteric vasculature of DOCA-salt rats. The media-to-lumen ratio was increased in DOCA-salt rats (10.3+/-0.9% vs 4.9+/-0.5% in Uni-Nx rats, P<0.01). Rosiglitazone and fenofibrate prevented the hypertrophic remodeling observed in DOCA-salt rats without affecting vascular stiffness. Rosiglitazone but not fenofibrate prevented endothelial dysfunction in pressurized mesenteric arteries. Finally, both rosiglitazone and fenofibrate prevented the vascular increase in superoxide anion production induced in DOCA-salt animals.. PPAR-alpha and -gamma activators were able to modulate endogenous production of ET-1 and had beneficial vascular effects in endothelin-dependent hypertension.

Topics: Animals; Blood Pressure; Body Weight; Endothelin-1; Endothelins; Extracellular Matrix; Fenofibrate; Hypertension; In Vitro Techniques; Male; Mesenteric Arteries; Oxygen; Protein Precursors; Rats; Rats, Inbred Dahl; Rats, Sprague-Dawley; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Rosiglitazone; Thiazoles; Thiazolidinediones; Transcription Factors; Tunica Media; Vascular Resistance; Vasodilator Agents

We tested the effect of selective endothelin ET(A) receptor blockade on the development renal damage in the Sabra rat model of genetic salt-sensitivity. Animals from the salt-sensitive (SBH/y) and salt-resistant strains (SBN/y) were either salt-loaded with deoxycorticosterone acetate and salt (DOCA) or fed a normal diet. Additional salt-loaded groups were also treated with the selective ET(A) antagonist darusentan (DA). Salt-loading in SBH/y increased systolic blood pressure by 75 mm Hg and urinary albumin excretion 23-fold (P<0.0001). Darusentan attenuated the rise of systolic blood pressure (50%) and urinary albumin excretion (63%, P<0.01, respectively). Salt-loading in SBH/y was associated with significant increased osteopontin mRNA expression as well as glomerulosclerosis and tubulointerstitial damage in the kidney (P<0.05, respectively). This was either significantly reduced or normalized by darusentan (P<0.05, respectively). Thus, darusentan confers a significant renal protection in the Sabra model of salt-sensitive hypertension.

Topics: Albuminuria; Animals; Body Weight; Desoxycorticosterone; Disease Models, Animal; Endothelin A Receptor Antagonists; Endothelin-1; Hypertension; Kidney; Kidney Diseases; Male; Organ Size; Osteopontin; Phenylpropionates; Pyrimidines; Rats; Rats, Inbred Strains; Receptor, Endothelin A; Receptor, Endothelin B; RNA, Messenger; Sialoglycoproteins; Sodium; Sodium Chloride, Dietary

The hypothesis that in normotensive offspring of hypertensive parents exercise training could influence the systemic release of endothelin (ET)-1 during a provocative testing protocol was tested.. The provocative handgrip test was performed in four groups of healthy young age-matched males: offspring of hypertensive parents following a regular swimming exercise regimen (group A, n = 14); offspring of hypertensive parents and leading a sedentary lifestyle (group B, n = 11); normal volunteers with no family history of hypertension: sedentary (group C, n = 10), and following a regular swimming regimen (group D, n = 10). The plasma ET-1 was measured at baseline, after 4 min of handgrip exercise at 50% maximal capacity and following 2 (R2) and 10 (R10) min of recovery from handgrip.. ET-1 plasma levels, within the normal range in all groups at baseline (group A 0.94 +/- 0.32 pg/ml, group B 0.84 +/- 0.26 pg/ml, group C 0.78 +/- 0.35 pg/ml, group D 0.85 +/- 0.26, p = NS) showed a progressive and significant increase in group B during and after handgrip exercise (peak handgrip 1.08 +/- 0.5 pg/ml, p = NS; R2 1.35 +/- 0.36 pg/ml, p < 0.05; R10 2.76 +/- 0.75 pg/ml, p < 0.01). Significant differences were found at R2 and R10 when the ET-1 levels measured in group B were compared to those observed in group A, group C and group D. Multivariate analysis demonstrated that the serum levels of ET-1 significantly contributed to predict handgrip-induced changes when the diastolic blood pressure was the dependent variable.. Routine aerobic exercise appeared to counteract the handgrip-induced abnormal release of plasma ET-1 and may favorably affect the preclinical endothelial alterations seen in healthy offspring of hypertensive parents.

Topics: Adult; Biomarkers; Blood Pressure; Body Height; Body Weight; Endothelin-1; Exercise; Exercise Therapy; Family Health; Heart Rate; Humans; Hypertension; Male; Multivariate Analysis; Reference Values; Risk Factors

Peroxisome proliferator-activated receptor (PPAR) activation may prevent cardiac hypertrophy and inhibit production of endothelin-1 (ET-1), a hypertrophic agent. The aim of this in vivo study was to investigate the effects of PPAR activators on cardiac remodeling in DOCA-salt rats, a model overexpressing ET-1. Unilaterally nephrectomized 16-week-old Sprague-Dawley rats (Uni-Nx) were randomly divided into 4 groups: control rats, DOCA-salt, DOCA-salt+rosiglitazone (PPAR-gamma activator, 5 mg/kg per day), and DOCA-salt+fenofibrate (PPAR-alpha activator, 100 mg/kg per day). After 3 weeks of treatment, mean arterial blood pressure was significantly increased in DOCA-salt by 36 mm Hg. Mean arterial blood pressure was normalized by coadministration of rosiglitazone but not by fenofibrate. Both PPAR activators prevented cardiac fibrosis and abrogated the increase in prepro-ET-1 mRNA content in the left ventricle of DOCA-salt rats. Coadministration of rosiglitazone or fenofibrate failed to prevent thickening of left ventricle (LV) walls as measured by echocardiography and the increase in atrial natriuretic peptide mRNA levels. However, rosiglitazone and fenofibrate prevented the decrease in LV internal diameter and thus concentric remodeling of the LV found in DOCA-salt rats. Taken together, these data indicate a modulatory role of PPAR activators on cardiac remodeling in mineralocorticoid-induced hypertension, in part associated with decreased ET-1 production.

Topics: Animals; Blood Pressure; Body Weight; Cardiomegaly; Collagen; Desoxycorticosterone; Endothelin-1; Endothelins; Fenofibrate; Fibrosis; Heart; Heart Ventricles; Hypertension; Myocardium; Protein Precursors; Rats; Rats, Sprague-Dawley; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Rosiglitazone; Thiazoles; Thiazolidinediones; Transcription Factors; Ventricular Remodeling

Ischemia-reperfusion (I/R) injury of the lung involves increased pulmonary vascular resistance. Prostaglandins are thought to have a beneficial effect in lung transplantation, but their mechanism in I/R injury is unknown. We investigated whether iloprost, a stable prostacyclin analogue, prevents I/R-associated pulmonary vascular dysfunction and whether it affects endothelin-1 (ET-1) balance.. In an isolated blood-perfusion model, we subjected lungs of Lewis rats to 45 minutes of ischemia at 37 degrees C and randomly allocated the lungs to 3 groups (n = 6 each): iloprost (33.3 nmol/liter) added to the perfusate before ischemia and reperfusion (ILO+IR), iloprost (33.3 nmol/liter) given only before reperfusion (ILO+R), and controls without iloprost treatment (ILO-).. Reperfusion induced marked pulmonary edema in non-treated controls (ILO-), which was attenuated in ILO+R lungs and completely prevented in ILO+IR lungs. At 60 minutes reperfusion, arterial oxygen tension was significantly greater in both ILO+R and ILO+IR lungs compared with ILO- controls. Mean pulmonary artery pressure and pulmonary vascular resistance were slightly decreased in the ILO+R and significantly decreased in the ILO+IR group compared with the ILO- controls. Plasma levels of big ET-1, measured in both afferent and efferent blood, showed that I/R results in increased pulmonary venous levels of big ET-1. Interestingly, the increased venoarterial ET-1 gradient in ILO- lungs decreased significantly in the ILO+IR group.. We demonstrated in an isolated lung perfusion model that iloprost ameliorates post-ischemic lung reperfusion injury and maintains an appropriate pulmonary ET-1 balance.

Topics: Animals; Body Weight; Disease Models, Animal; Endothelin-1; Iloprost; Lung; Male; Models, Cardiovascular; Oxygen; Pulmonary Circulation; Pulmonary Edema; Pulmonary Gas Exchange; Pulmonary Wedge Pressure; Rats; Rats, Inbred Lew; Reperfusion Injury; Respiratory Distress Syndrome; Severity of Illness Index; Statistics as Topic; Vascular Resistance; Vasodilator Agents

The present study evaluated the importance of ovarian functions and the renin-angiotensin system in the progression of the right ventricular (RV) hypertrophy. Female Sprague-Dawley rats were bilaterally ovariectomized (Ovx) and injected with monocrotaline (MCT, 60 mg/kg, sc). Four weeks after MCT-treatment, only the male and Ovx female rats showed marked RV hypertrophy. The hypertrophied RV of the male-MCT and Ovx-MCT rats exhibited remarkably elevated renin mRNA levels. Gene expression levels of angiotensinogen, TGF-beta1, and endothelin-1 in the hypertrophied RV also increased, but to the less degree than did the renin mRNA. To investigate beneficial effects of estrogen or enalapril on progression of the pulmonary hypertension and RV hypertrophy, histological changes of the lung and heart were examined. Sham-MCT female rats showed histological changes indicating pulmonary hypertension without RV hypertrophy. In contrast, Ovx-MCT rats showed marked RV hypertrophy with pathological changes, denoting severe pulmonary and myocardial injuries. Estrogen-or enalapril-treated Ovx-MCT rats did not show RV hypertrophy, and showed remarkably ameliorated ultrastructural changes in the lung and RV. These results from this rat model suggest that both estrogen and inhibition of the renin-angiotensin system have protective functions against the development of the pulmonary hypertension and cardiac remodeling.

Topics: Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Body Weight; Densitometry; Disease Progression; Enalapril; Endothelin-1; Estrogens; Female; Hypertrophy, Right Ventricular; Male; Microscopy, Electron; Monocrotaline; Ovariectomy; Rats; Rats, Sprague-Dawley; Renin; Reverse Transcriptase Polymerase Chain Reaction; RNA; RNA, Messenger; Sex Factors; Transforming Growth Factor beta; Transforming Growth Factor beta1; Ventricular Remodeling

Heme oxygenase (HO) isoforms, HO-1, and HO-2, are responsible for heme breakdown to iron and carbon monoxide (CO). HO may respond to oxidative stress and may modulate the expression of vasoactive factors like nitric oxide (NO). Since diabetes induced oxidative stress may change HO, the present study examined whether diabetes is associated with HO alterations, its relationship with NO, endothelin-1(ET-1) and the functional significance.. Male SD rats with Streptozotocin induced diabetes were investigated after six-weeks. Poorly controlled diabetic animals were randomized to one of three treatment groups (n = 6 each group); a) untreated, b) HO-1 inhibitor SnPP-IX (50 micromol/kgIP/day), c) NO donor molsidomine (120 mg/L PO/day) and were compared with age and sex matched non diabetic control animals with or without SnPP-IX treatment. Color Doppler ultrasound analysis was used to determine retinal resistivity index (RI). mRNA for HO-1, HO-2, ET-1, eNOS and iNOS were analyzed with competitive RT-PCR. HO distribution in the retina was investigated by immunocytochemistry.. Diabetic animals expressed lower body weight, higher blood glucose and increased glycated hemoglobin levels. HO-1 and HO-2 immuno-reactivity were identified in the retina. Diabetes induced increased RI was associated with up-regulation of both ET-1 and HO-1 mRNA expression but not eNOS or iNOS mRNA. Both SnPP-IX and molsidomine treatments prevented a diabetes increase of RI, in spite of increased ET-1 expression and were associated with increased iNOS mRNA.. The present data suggests that the HO system is up-regulated in short term diabetes leading to HO and NO interactions which may modulate vascular function in the retina.

Topics: Animals; Blood Glucose; Body Weight; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Endothelin-1; Enzyme Inhibitors; Glycated Hemoglobin; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Male; Metalloporphyrins; Molsidomine; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Protoporphyrins; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Up-Regulation

This study assessed the behavioral and dendritic structural effects of combining subdural motor cortical electrical stimulation with motor skills training following unilateral sensorimotor cortex lesions in adult male rats. Rats were pre-operatively trained on a skilled forelimb reaching task, the Montoya staircase test, and then received endothelin-1 induced ischemic lesions of the sensorimotor cortex. Ten to 14 days later, electrodes were implanted over the peri-lesion cortical surface. Rats subsequently began 10 days of rehabilitative training on the reaching task in 1 of 3 conditions: 1. 50 Hz stimulation during training, 2. 250 Hz stimulation during training or 3. no stimulation. No significant difference in performance was found between the 250 Hz and no stimulation groups. The 50 Hz stimulation group had significantly greater rates of improvement with the impaired forelimb in comparison to 250 Hz and no stimulation groups combined. Fifty Hz stimulated animals also had a significant increase in the surface density of dendritic processes immunoreactive for the cytoskeletal protein, microtubule-associated protein 2, in the peri-lesion cortex compared to the other groups. These results support the efficacy of combining rehabilitative training with cortical electrical stimulation to improve functional outcome and cortical neuronal structural plasticity following sensorimotor cortical damage.

Topics: Analysis of Variance; Animals; Behavior, Animal; Body Weight; Brain Ischemia; Cell Count; Cerebral Cortex; Corpus Striatum; Dendrites; Disease Models, Animal; Dose-Response Relationship, Radiation; Electric Stimulation; Electrodes; Endothelin-1; Forelimb; Immunohistochemistry; Male; Microtubule-Associated Proteins; Motor Skills; Neuronal Plasticity; Rats; Rats, Long-Evans; Recovery of Function; Sensory Thresholds; Staining and Labeling

Vascular function plays a preponderant role in the pulmonary changes that occur with maturation, during birth, and in the development of pulmonary hypertension. This study was designed to characterize the changes in vasoactivity occurring in broiler and Leghorn chickens from late embryonic life to 5 wk of age. Pulmonary arteries were isolated from 19- and 20-d-old embryos, hatchlings, and 1-, 2-, 3-, 4- and 5-wk-old chickens of both lines and subjected to KCl (45.4 mM)- and endothelin-1 (10(-7.5) M)-induced vasoconstrictions followed by acetylcholine (ACh; 10(-5), 10(-6) and 10(-7) M)- and papaverine (10(-4) M)-induced vasodilations. Vasoconstrictions were greatest at hatch and rapidly declined thereafter, whereas vasodilations were greatest in 20-d-old embryos except with 10(-7) M ACh. Broilers grew faster than Leghorns and had lower vasodilation responses to all concentrations of ACh at 2 and 5 wk of age. Broilers also had greater right-to-total ventricular weight ratios at 5 wk of age, whereas ratios were greater in Leghorn embryos at 20 d of incubation and at hatch. Thus, for a brief period before hatch there is a significant increase in pulmonary endothelium-dependent vasodilation capacity in the chicken embryo, which may aid in the transition from chorioallantoic to pulmonary respiration. The absence of differences in vasodilator capacity between broilers and Leghorns before hatch suggests that the differences in pulmonary artery relaxation capacity and pulmonary hypertension observed after hatch in broilers are not necessarily acquired during incubation but may be related to rapid growth of the broiler chicken.

Topics: Acetylcholine; Aging; Animals; Body Weight; Chick Embryo; Chickens; Endothelin-1; Organ Size; Papaverine; Potassium Chloride; Pulmonary Artery; Vasoconstriction; Vasodilation

The aim of this study was to show whether the decrease in blood pressure induced by Mg supplementation in deoxycorticosterone acetate - salt (DOCA-salt) hypertensive rats is associated with mechanical modifications of blood vessels and (or) changes in tissular production and (or) vasoconstrictor activity to endothelin-1. DOCA-salt treatment increased blood pressure, media thickness, cross-sectional area, and lumen diameter of carotid arteries. Distensibility and incremental elastic modulus versus stress were not altered in carotid arteries, suggesting that the DOCA-salt vessel wall adapts structurally to preserve its blood pressure buffering capacity. Magnesium supplementation attenuated DOCA-salt hypertension. In comparison with normotensive rats, systolic, mean, and pulse pressures were higher whereas diastolic pressure was not different in Mg-supplemented DOCA-salt rats. Magnesium supplementation did not significantly modify the elastic parameters of carotid arteries. In resistance mesenteric arteries, DOCA-salt hypertension induces an inward hypertrophic remodeling. Magnesium supplementation attenuates wall hypertrophy and increases lumen diameter to the normotensive diameter, suggesting a decrease in peripheral resistance. Magnesium supplementation normalizes the altered vasoconstrictor activity of endothelin-1 in mesenteric arteries and attenuates endothelin-1 overproduction in kidney, left ventricle, and aorta of DOCA-salt rats. These findings suggest that Mg supplementation prevents blood pressure elevation by attenuating peripheral resistance and by decreasing hypertrophic effect of endothelin-1 via inhibition of endothelin-1 production.

Topics: Animals; Arteries; Blood Pressure; Body Weight; Calcium; Carotid Arteries; Desoxycorticosterone; Diet; Endothelin-1; Heart Rate; Hypertension; In Vitro Techniques; Magnesium; Male; Mesenteric Arteries; Organ Size; Rats; Rats, Sprague-Dawley; Vascular Resistance; Vasoconstriction

Aging impairs endothelial function and the vascular tone regulation, although the precise mechanism remains unclear. Endothelin-1 (ET-1) is a potent vasoconstrictor peptide produced by vascular endothelial cells. Because ET-1 has a potent vasoconstrictor effect on vessels, it may be involved in the regulation of vascular tonus. We hypothesized that aging causes a decrease in ET-1 expression in aorta, and that exercise training improves the aging-induced decrease in ET-1 expression in aorta. This study was performed to examine whether gene expression of ET-1 in the aorta of rats is altered by aging and subsequent exercise training. We studied expression of ET-1 mRNA in the aortas of sedentary young rats (Sedentary young group, 4 months old), sedentary aged rats (Sedentary aged group, 23 months old), and swim trained aged rats (Training aged group, 23 months old; swimming training for 8 weeks, 5 days/week, 90 min/day). The expression of ET-1 mRNA in the aorta was analysed by real-time quantitative PCR. Body weight and resting heart rate were significantly lower in the Training aged group compared with the Sedentary aged group. These results suggest that the Training aged rats exhibited physiological effects from exercise training. The expression of ET-1 mRNA in the aorta was markedly lower in Sedentary aged group compared with the Sedentary young group, whereas it was significantly higher in Training aged group compared with the Sedentary aged group. These results show that the expression of ET-1 mRNA in the aorta is decreased by aging, and that the expression is increased by exercise training. Therefore, the present study provides a possibility that exercise training improves endothelial function through up-regulation of the aging-induced decrease in ET-1 expression in the aorta.

Topics: Aging; Animals; Aorta; Body Weight; Endothelin-1; Endothelium, Vascular; Gene Expression; Heart Rate; Male; Physical Conditioning, Animal; Physical Exertion; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

We have investigated the effect of potassium (E)-N-[6-methoxy-5-(2-methoxyphenoxy)-2-(pyrimidin-2-yl) pyrimidin-4-yl]-2-phenylenthenesulfonamidate (YM598), a selective endothelin ET(A) receptor antagonist, on renal function in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of type II diabetes. YM598 (0.1 or 1 mg kg(-1)), enalapril (5 mg kg(-1)), an angiotensin-converting enzyme inhibitor, or vehicle was administered once daily by gastric gavage to 22-week-old male Otsuka Long-Evans Tokushima Fatty rats for 32 weeks. Enalapril but not YM598 mildly lowered blood pressure in the diabetic rats. YM598 blunted the development of albuminuria in a dose-dependent manner. High dose of YM598 reduced albuminuria comparable to enalapril. Urinary endothelin-1 excretion was greater in the diabetic than in the control rats, and was not substantially influenced by the agents. These data suggest that endothelin is involved in the progression of diabetic nephropathy in Otsuka Long-Evans Tokushima Fatty rats, and an endothelin ET(A) receptor antagonist may be useful for the treatment of diabetic nephropathy.

Topics: Animals; Blood Pressure; Body Weight; Diabetic Nephropathies; Dose-Response Relationship, Drug; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Kidney Function Tests; Male; Pyrimidines; Rats; Rats, Inbred OLETF; Receptor, Endothelin A; Sulfonamides

IGF-I has been suggested to be of importance for cardiovascular structure and function, but the relative role of locally produced and liver-derived endocrine IGF-I remains unclear. Using the Cre-LoxP recombination system, we have previously created transgenic mice with a liver-specific, inducible IGF-I knockout (LI-IGF-I-/-). To examine the role of liver-derived IGF-I in cardiovascular physiology, liver-derived IGF-I was inactivated at 4 wk of age, resulting in a 79% reduction of serum IGF-I levels. At 4 months of age, systolic blood pressure (BP) was increased in LI-IGF-I-/- mice. Echocardiography showed increased posterior wall thickness in combination with decreased stroke volume and cardiac output, whereas other systolic variables were unchanged, suggesting that these cardiac effects were secondary to increased peripheral resistance. Acute nitric oxide-synthase inhibition increased systolic BP more in LI-IGF-I-/- mice than in control mice. LI-IGF-I-/- mice showed impaired acetylcholine-induced vasorelaxation in mesenteric resistance vessels and increased levels of endothelin-1 mRNA in aorta. Thus, the increased peripheral resistance in LI-IGF-I-/- mice might be attributable to endothelial dysfunction associated with increased expression of endothelin-1 and impaired vasorelaxation of resistance vessels. In conclusion, our findings suggest that liver-derived IGF-I is involved in the regulation of BP in mice.

Topics: Acetylcholine; Animals; Blood Pressure; Body Weight; Cardiac Output; Creatinine; Echocardiography; Endothelin-1; Insulin-Like Growth Factor I; Liver; Mesenteric Arteries; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Knockout; Myocardium; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Norepinephrine; Organ Size; Renin; RNA, Messenger; Vasodilation

Vasoconstrictor prostanoids have been implicated in abnormal vasomotion in atherosclerosis and hypertension.. Using lean and diet-induced obese mice, we investigated whether obesity affects vascular function or expression of genes involved in prostanoid action.. In lean C57BL/6J mice, at high concentrations acetylcholine caused endothelium-dependent contractions in the carotid artery but not in the aorta. Endothelium-dependent contractions to acetylcholine were blocked by the non-selective cyclooxygenase (COX) inhibitors indomethacin and meclofenamate, or a prostaglandin H2/thromboxane A2 receptor antagonist, but not by inhibitors of COX-2, thromboxane synthase or cytochrome P450 monooxygenase. Obesity increased endothelium-dependent contractions to acetylcholine in the carotid artery, and prostanoid-mediated vasoconstriction was now present in the aorta. Similarly, contractions to endothelin-1 were largely blocked by meclofenamate and were increased in the aorta of obese mice. Real-time quantitative polymerase chain reaction analysis of the thromboxane receptor gene in the carotid artery revealed a robust upregulation in obese animals (18-fold, 0.05); in comparison, obesity had a less pronounced effect on thromboxane synthase (2.1-fold increase, 0.05), or preproendothelin-1 gene expression (4.2-fold increase, 0.05).. These data demonstrate that obesity augments prostanoid-dependent vasoconstriction and markedly increases vascular thromboxane receptor gene expression. These changes are likely to promote the development of vascular disease, hypertension and thrombosis associated with obesity.

Topics: Acetylcholine; Animals; Body Weight; Carotid Arteries; Endothelin-1; Endothelins; Gene Expression; Hypertension; Male; Mice; Mice, Inbred C57BL; Nitroprusside; Obesity; Protein Precursors; Receptors, Thromboxane; RNA, Messenger; Thromboxane-A Synthase; Vasoconstriction; Vasodilator Agents

Topics: Angiotensin II; Animals; Blood Glucose; Blood Pressure; Body Weight; Catecholamines; Diabetes Mellitus, Experimental; Endothelin-1; Hypertension, Renal; In Vitro Techniques; Male; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Renal Circulation; Thromboxanes; Vasoconstrictor Agents

We evaluated the cardioprotective effects of long-term treatment with celiprolol (for 5 weeks), a specific beta(1)-adrenoceptor antagonist with a weak beta(2)-adrenoceptor agonist action, on endothelin-1 and transforming growth factor (TGF)-beta(1) expression and cardiovascular remodeling in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Upregulated preproendothelin-1, endothelin ET(A) receptor, TGF-beta(1), c-fos, and type I collagen expression and extracellular signal-regulated kinase activities were suppressed by celiprolol. Celiprolol effectively inhibited vascular lesion formation such as medial thickness and perivascular fibrosis. These observations suggested that extracellular signal-regulated kinase and c-fos gene pathway may contribute to the cardiovascular remodeling of DOCA rats, and that cardioprotective effects of celiprolol on cardiovascular remodeling may be mediated, at least in part, by suppressed expression of endothelin-1 and TGF-beta(1).

Topics: Adrenergic beta-Antagonists; Animals; Blotting, Western; Body Weight; Celiprolol; Desoxycorticosterone; Endothelin-1; Gene Expression Regulation; Heart Ventricles; Hemodynamics; Hypertension; Male; Mitogen-Activated Protein Kinases; Organ Size; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Transforming Growth Factor beta; Transforming Growth Factor beta1; Ventricular Remodeling

It is well established that angiotensin-converting enzyme (ACE) inhibitors (ACEI) reduce blood pressure (BP) and hypertrophy of the left ventricle and vessels. The aim of our study was to compare chemically different ACEIs regarding their ability to modulate left ventricular and media hypertrophy, ACE activity and plasma endothelin-1 concentrations in spontaneously hypertensive rats (SHRs).. After establishing equi-effective dose regimes, SHRs were treated (3 months) with captopril, enalapril, fosinopril or ramipril (2 x 25, 10, 20 or 1 mg/kg per day or corresponding 1% doses for studying blood pressure-independent effects).. Systolic blood pressure was reduced in SHRs receiving high doses of captopril, enalapril, fosinopril or ramipril (-61, -54, -35 and -47 mmHg), whereas low doses were ineffective. Left ventricular weight was decreased in animals treated with high doses (captopril/enalapril/fosinopril/ramipril: -17/-19/-17/-19%), but not low doses of agents. Media thickness of thoracal aorta was reduced by administering high doses (captopril/enalapril/fosinopril/ramipril: -31/-32/-27/-26%) and low doses (-16/-22/-22/-19%) of agents. ACE activity was reduced in heart, aorta and kidney of rats treated with high and low doses of all ACE inhibitors, whereby high doses showed more pronounced effects. Plasma endothelin-1 concentrations were not altered. A blood-pressure-ineffective treatment with an AT -antagonist revealed similar effects on cardiovascular hypertrophy.. ACEIs reduce cardiovascular hypertrophy uniformly via an AT -receptor- mediated mechanism, reinforcing the opinion that ACEI effects are indeed class effects. The significance of local renin-angiotensin systems was confirmed by antihypertrophic effects in the aorta that were apparent in the absence of any blood pressure reduction.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta, Thoracic; Blood Pressure; Body Weight; Captopril; Circadian Rhythm; Dose-Response Relationship, Drug; Enalapril; Endothelin-1; Fosinopril; Hypertrophy, Left Ventricular; Male; Peptidyl-Dipeptidase A; Ramipril; Rats; Rats, Inbred SHR

The aryl hydrocarbon receptor (AhR) is a member of the basic helix loop helix PAS (Per-ARNT-SIM) transcription family, which also includes hypoxiainducible factor-1alpha (HIF-1alpha) and its common dimerization partner AhR nuclear translocator (ARNT). Following ligand activation or hypoxia, AhR or HIF-1alpha, respectively, translocate into the nucleus, dimerize with ARNT, and regulate gene expression. Mice lacking the AhR have been shown previously to develop cardiac enlargement. In cardiac hypertrophy, it has been suggested that the myocardium becomes hypoxic, increasing HIF-1alpha stabilization and inducing coronary neovascularization, however, this mechanism has not been demonstrated in vivo. The purpose of this study was to investigate the cardiac enlargement reported in AhR(-/-) mice and to determine if it was associated with myocardial hypoxia and subsequent activation of the HIF-1alpha pathway. We found that AhR(-/-) mice develop significant cardiac hypertrophy at 5 mo. However, this cardiac hypertrophy was not associated with myocardial hypoxia. Despite this finding, cardiac hypertrophy in AhR(-/-) mice was associated with increased cardiac HIF-1alpha protein expression and increased mRNA expression of the neovascularization factor vascular endothelial growth factor (VEGF). These data demonstrate that the development of cardiac hypertrophy in AhR(-/-) mice not associated with myocardial hypoxia, but is correlated with increased cardiac HIF-1alpha protein and VEGF mRNA expression.

Topics: Age Factors; Animals; Atrial Natriuretic Factor; Biomarkers; Body Weight; Cardiac Myosins; Cardiomegaly; Disease Models, Animal; Endothelin-1; Gene Expression Regulation; Heart Ventricles; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Male; Mice; Mice, Mutant Strains; Models, Cardiovascular; Myocardium; Myosin Heavy Chains; Myosin Light Chains; Nonmuscle Myosin Type IIB; Organ Size; Phenotype; Rats; Receptors, Aryl Hydrocarbon; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Statistics as Topic; Time Factors; Transcription Factors; Vascular Endothelial Growth Factor A

The aims of the present study were to determine the effects of endothelin ET(A) receptor antagonism on carbon monoxide (CO)-induced cardiac hypertrophy and endothelin-1 (ET-1) expression and to compare myocardial effects of chronic nicotine with CO exposure. Female Sprague-Dawley rats (n = 84) were randomized to three groups exposed 20 h/day to CO (200 ppm), nicotine (500 microg/m3), or air for 14 consecutive days. In each exposure group, animals were randomized to ET(A) receptor antagonist LU 135252 in drinking water (0.5 mg/ml) or placebo. Myocardial ET-1 and atrial natriuretic peptide (ANP) expression was measured by competitive RT-PCR and plasma ET-1 by immunoassay. Carboxyhemoglobin was 22.1 +/- 0.3% in CO-exposed animals and 2.8 +/- 0.3% in controls. Plasma nicotine was 57 +/- 7 ng/ml and plasma cotinine was 590 +/- 23 ng/ml in nicotine-exposed animals and below detection levels in controls. CO exposure induced a 21% increase in right ventricular hypertrophy (p < 0.01), a 7% increase in left ventricular hypertrophy (p < 0.01), a 25% increase in right ventricular ET-1 expression (p < 0.05), and an eightfold increase in ANP expression (p = 0.08). ET(A) receptor antagonism reduced right ventricular hypertrophy by 60% (p < 0.05) with no significant effect on left ventricular hypertrophy or myocardial ET-1 expression. Chronic nicotine exposure did not significantly affect cardiac weights or ANP and ET-1 expression. We conclude that ET(A) receptor antagonism reduces right ventricular hypertrophy induced by chronic CO exposure, whereas CO-induced myocardial ET-1 expression remains unchanged.

Topics: Animals; Atmosphere Exposure Chambers; Atrial Natriuretic Factor; Body Weight; Carbon Monoxide; Cardiomegaly; Endothelin Receptor Antagonists; Endothelin-1; Female; Nicotine; Nicotinic Agonists; Organ Size; Phenylpropionates; Pyrimidines; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; RNA, Messenger

Increased endothelin-1 (ET-1) or aldosterone may be associated with promotion of cardiovascular hypertrophy and fibrosis. We evaluated whether the selective ETA receptor-antagonist BMS 182874 (BMS) prevents cardiac and vascular collagen deposition and hypertrophy in aldosterone-infused rats. Rats received subcutaneous aldosterone (0.75 microg/h) and 1% sodium chloride in drinking water +/- BMS (40 mg/kg per day in food) for 6 weeks. Heart and aorta were cross-sectioned and stained with Sirius red. Heart weight did not change with either aldosterone infusion or BMS treatment. Cardiac and aortic interstitial and perivascular collagen were quantified with videomorphometry. Aortic collagen and media cross-sectional area were significantly increased 3.5-fold (P < .01) and 1.13-fold (P < .05), respectively, with aldosterone infusion and decreased in BMS-treated rats (P < .05, P < .001, respectively). Aldosterone infusion increased interstitial and perivascular collagen in the left (1.6- and 2.7-fold, P < .05 and P < .01, respectively) and right ventricle (1.5- and 1.7-fold, P > .05 and P < .05, respectively). BMS prevented collagen deposition except for interstitial collagen in the right ventricle. Cardiac and aortic fibrosis were significantly increased in aldosterone-infused hypertensive rats. The ETA receptor antagonist prevented cardiac and aortic collagen deposition and aortic hypertrophy. This suggests a role for ET-1 in fibrosis of heart and large vessels in conditions associated with mineralocorticoid excess.

Topics: Aldosterone; Animals; Antihypertensive Agents; Aorta; Aortic Diseases; Blood Pressure; Body Weight; Cardiomyopathies; Collagen; Dansyl Compounds; Endothelin Receptor Antagonists; Endothelin-1; Fibrosis; Heart; Hypertrophy; Male; Myocardium; Organ Size; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A

To determine the role of endothelin-1 (ET-1) and its receptors in salt-sensitive hypertension induced by sensory nerve degeneration, selective ET(A) antagonist (ABT-627) and ET(B) antagonist (A-192621) were used. Newborn Wistar rats were given vehicle or 50 mg/kg capsaicin subcutaneously on the first and second days of life. After the weaning period, male rats were divided into eight groups, and subjected to the following treatments for 2 weeks: control + normal salt diet (Con+NS, 0.5%), control + high salt diet (Con+HS, 4%), control + high salt diet + ABT-627 (Con+HS+ABT-627), control + high salt diet + A-192621 (Con+HS+A-192621), capsaicin + normal salt diet (Cap+NS), capsaicin + high salt diet (Cap+HS), capsaicin + high salt diet + ABT-627 (Cap+HS+ABT-627), capsaicin + high salt diet + A-192621 (Cap+HS+A-192621). Both ABT-627 (5 mg/kg/d) and A-192621 (30 mg/kg/d) were given by oral gavage twice a day. Mean arterial pressure (MAP, mm Hg) was higher in Con+HS+A-192621 (141 +/-11) than in Con+NS (94 +/- 10), Con+HS (95 +/- 5), and Con+HS+ABT-627 (97 +/- 6) (P<0.05). MAP was also higher in Cap+HS (152 +/- 6) and Cap+HS+A-192621 (180 +/- 7) than in Cap+NS (99 +/- 3) and Cap+HS+ABT-627 (104 +/- 5) (P<0.05), and it was higher in Cap+HS+A-192621 than in Cap+HS (P<0.05). Enzyme immunometric assay showed that ET-1 plasma concentration (pg/mL) was higher in Con+HS+A-192621 (7.59 +/- 0.78) than in Con+NS (2.68 +/- 0.56), Con+HS (2.50 +/- 0.92), and Con+HS+ABT-627 (3.54 +/- 0.79) (P<0.05). ET-1 plasma concentration was also higher in Cap+HS (8.95 +/-.16), Cap+HS+ABT-627 (9.82 +/- 1.22) and Cap+HS+A-192621 (10.97 +/- 0.57) than in Cap+NS (3.06 +/- 0.73) (P<0.05). We conclude that blockade of the ET(A) receptor prevents the development of salt sensitive hypertension induced by sensory nerve degeneration, indicating that activation of the ET(A) receptor by increased plasma ET-1 level contributes to elevation of blood pressure in this model. In contrast, blockade of the ET(B) receptor leads to an increase in blood pressure in both normal and sensory nerve degenerated rats fed a high salt diet. These results suggest that ET(B) plays an antihypertensive role in response to high salt intake under both normal and sensory nerve degenerated conditions.

Topics: Animals; Body Weight; Endothelin-1; Female; Hypertension; Nerve Degeneration; Rats; Rats, Wistar; Receptor, Endothelin A; Receptors, Endothelin; Salts; Sensory Receptor Cells

The effect of capsaicin (0.1 microM) on heart rate and coronary flow was studied in Langendorff-perfused heart from streptozotocin-induced (50 mg/kg i.v.) diabetic rats where sensory neuropathy developed. In hearts from animals 4- and 8-week diabetes baseline heart rate and coronary flow decreased from 317.9 +/- 2.9 b.p.m. and 13.4 +/- 0.7 m/min to 255.1 +/- 12.7 and 219.8 +/- 2.8 b.p.m. and 8.9 +/- 0.6 and 10.0 +/- 0.1 ml/min (P<0.05), respectively. Capsaicin significantly decreased both variables in either normal or 4-week diabetic animals its effects, however, on coronary flow or heart rate were missing in preparations from 8-week diabetic rats. Endothelin-1 (0.1 nM), the putative mediator of the capsaicin effect, significantly decreased heart rate and coronary flow irrespective of the presence or absence of diabetes. In the femoral nerve of streptozotocin-treated animals conduction velocity involving both fast conducting A- and slow-conducting C-fibres was decreased proportional to the duration of the pre-existing diabetic state. It is concluded that in insulin deficient diabetes the diminished responses evoked by capsaicin on heart rate and coronary flow are signs of sensory neuropathy. This is related to a feeble endothelin release from sensory nerve endings without changes in post-receptor mechanisms mediating the endothelin effects.

Topics: Animals; Blood Glucose; Body Weight; Capsaicin; Coronary Circulation; Diabetes Mellitus, Experimental; Endothelin-1; Heart Rate; In Vitro Techniques; Insulin; Male; Nerve Fibers; Neural Conduction; Neurons, Afferent; Rats; Rats, Wistar

Hyperinsulinemia, a primary feature of insulin resistance, is associated with increased endothelin-1 (ET-1) activity. This study determined the vascular response to ET-1 and receptor binding characteristics in small mesenteric arteries of insulin-resistant (IR) rats. Rats were randomized to control (C) (n = 32) or IR (n = 32) groups. The response to ET-1 was assessed (in vitro) in arteries with (Endo+) and without (Endo-) endothelium. In addition, arteries (Endo+) were pretreated with the ET(B) antagonist A-192621 or the ET(A) antagonist A-127722. Finally, binding characteristics of [(125)I]ET-1 were determined. Results showed that in Endo+ arteries the maximal relaxation (E(max)) to ET-1 was similar between C and IR groups; however, the concentration at 50% of maximum relaxation (EC(50)) was decreased in IR arteries. In Endo- arteries, the E(max) to ET-1 was enhanced in both groups. Pretreatment with A-192621 enhanced the E(max) and EC(50) to ET-1 in both groups. In contrast, A-127722 inhibited the ET-1 response in all arteries in a concentration-dependent manner; however, a greater ET-1 response was seen at each concentration in IR arteries. Maximal binding of [(125)I]ET-1 was increased in IR versus C arteries although the dissociation constant values were similar. In conclusion, we found the vasoconstrictor response to ET-1 is enhanced in IR arteries due to an enhanced expression of ET receptors and underlying endothelial dysfunction.

Topics: Animals; Body Weight; Dose-Response Relationship, Drug; Endothelin Receptor Antagonists; Endothelin-1; Hyperinsulinism; In Vitro Techniques; Insulin Resistance; Iodine Radioisotopes; Male; Mesenteric Arteries; Muscle, Smooth, Vascular; Pyrrolidines; Radioligand Assay; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin

Mechanisms underlying hepatic microcirculatory failure during endotoxemia are incompletely understood. Because endothelin-1 (ET-1) has been implicated in endotoxin-induced liver injury, we investigated the hepatic ET-1 system in endotoxin-treated rats.. Rats were treated with endotoxin (Escherichia coli lipopolysaccharide; 3 mg/kg, i.p.), and various determinations were made 24 h later.. Endotoxin treatment caused 11.2 +/- 1.6% weight loss, a decrease in mean arterial pressure (MAP; 96 +/- 5 mmHg vs 108 +/- 3 mmHg; P < 0.05) and an increase in portal pressure (11.6 +/- 1.3 mmHg vs 7.4 +/- 1 mmHg; P < 0.02). No significant changes in the serum levels of liver enzymes or hepatocellular necrosis were observed. Endotoxin caused increases in hepatic ET-1 (from 345 +/- 31 to 565 +/- 38 pg/g; P < 0.01), ET-1 receptor density (from 179 +/- 16 to 340 +/- 26 fmol/mg; P < 0.02), and mRNA expression of preproendothelin-1, and ET(A) and ET(B) receptors. While the serum nitric oxide (nitrite +/- nitrate) concentration was increased in endotoxin-treated rats, that of ET-1 remained unchanged. A mixed ET(A)/ET(B) receptor antagonist, TAK-044 (10 mg/kg, i.v.), reduced the weight loss from 11.2 +/- 1.6% to 5.9 +/- 2.9% (P < 0.05) and the portal pressure from 11.6 +/- 1.3 mmHg to 8.6 +/- 0.7 mmHg (P < 0.05) in endotoxin-treated rats. The mixed ET(A)/ET(B) receptor antagonist also caused an increase in serum ET-1 concentration, but did not affect serum nitric oxide and MAP in endotoxin-treated rats.. These results suggest that the upregulated hepatic ET-1 system is an important mechanism of increased portal resistance and related complications of endotoxemia.

Topics: Animals; Blood Pressure; Body Weight; Endothelin-1; Endotoxemia; Endotoxins; Liver; Male; Nitric Oxide; Peptides, Cyclic; Rats; Rats, Sprague-Dawley; Receptors, Endothelin; RNA, Messenger; Up-Regulation

Angiotensin II (Ang II) has been shown to stimulate cardiac growth and collagen synthesis in cultured vascular smooth muscle cells and to increase fibroblast proliferation. Chronic infusion with Ang II increases blood pressure and activates growth mechanisms to produce hypertrophy of the heart. This study investigated the effects of an Ang II type 1 receptor antagonist, TCV-116, on preproendothelin-1 (preproET-1), ETA receptor and platelet-derived growth factor (PDGF) A-chain expression in the left ventricle of Wistar-Kyoto rats treated for 2 weeks with Ang II (200 ng x kg(-1) x min(-1)), and the relation of these effects to myocardial remodeling. Rats given Ang II alone (ANGII-V) were compared with rats also receiving TCV-116 (ANGII-TCV). In both groups, blood pressure was similar and significantly higher than in control rats. The preproET-1, ET(A) receptor and PDGF A-chain expressions in the left ventricle were significantly increased in ANGII-V compared with control rats, and were significantly suppressed in ANGII-TCV compared with ANGII-V rats. ANGII-V rats showed a significant increase of the type I collagen expression, wall-to-lumen ratio, perivascular fibrosis, and myocardial fibrosis, with all these parameters being significantly improved by TCV-116. Myocardial remodeling in Ang II-induced hypertensive rats was significantly ameliorated by a subdepressor dose of TCV-116, which may have been due to a decrease in ET-1 and PDGF A-chain expression in the left ventricle.

Topics: Angiotensin II; Angiotensin Receptor Antagonists; Animals; Antihypertensive Agents; Benzimidazoles; Biphenyl Compounds; Blotting, Western; Body Weight; Collagen; Endothelin Receptor Antagonists; Endothelin-1; Heart Ventricles; Hemodynamics; Hypertension; Male; Organ Size; Platelet-Derived Growth Factor; Rats; Rats, Inbred WKY; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Receptor, Endothelin A; Receptors, Endothelin; Reverse Transcriptase Polymerase Chain Reaction; Tetrazoles; Ventricular Remodeling

It is unclear why a subgroup of patients with essential hypertension develop salt-sensitive hypertension with progression of target organ damage over time. We evaluated the role of the renal endothelin (ET) system in the stroke-prone spontaneously hypertensive rat (SHRSP) model of salt-sensitive spontaneous hypertension (SS-SH) compared with the spontaneously hypertensive rat (SHR) model of salt-resistant spontaneous hypertension (SR-SH). Both strains were studied after either sham-operation on a normal diet (Sham) or after unilateral nephrectomy and high NaCl loading (NX-NaCl) with 4% NaCl in diet for 6 weeks (n=10, respectively). Systolic blood pressure (SBP) increased only in SHRSP-NX-NaCl compared with SHRSP-Sham (250+/-6 versus 172+/-5 mm Hg, P:<0.0001). SBP remained unchanged in SHR-NX-NaCl compared with SHR-Sham. In SHRSP-NX-NaCl animals, urinary albumin and ET-1 excretion, renal ET-1 mRNA expression, glomerulosclerosis index, and tubulointerstitial damage index were elevated compared with SHRSP-Sham (P:<0.05, respectively), whereas no significant changes were found in SHR after NX-NaCl. Urinary sodium excretion (U(Na(+))) was significantly reduced by 38% in SHRSP-NX-NaCl compared with SHR-NX-NaCl (P:<0.005, respectively). SHR animals showed a similar increase in both renal ET(A) and ET(B) receptor densities after NX-NaCl (2.2-fold, P:<0.05). In contrast, SHRSP-NX-NaCl developed a significantly more pronounced increase in ET(A) compared with ET(B) binding (4.7-fold versus 2.4-fold, P:<0.05, compared with SHRSP-Sham, respectively), resulting in a significant 2.1-fold increase in ET(A)/ET(B) receptor ratio only in the SHRSP-NX-NaCl (P:<0.05). Thus, activation of the renal ET system together with an increased ET(A)/ET(B) receptor ratio may contribute to the development and progression of SS-SH.

Topics: Albuminuria; Animals; Aspartic Acid Endopeptidases; Binding, Competitive; Blood Pressure; Blotting, Northern; Body Weight; Endothelin-1; Endothelin-Converting Enzymes; Hypertension; Kidney; Kidney Diseases; Male; Metabolic Clearance Rate; Metalloendopeptidases; Nephrectomy; Organ Size; Proteinuria; Rats; Rats, Inbred SHR; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; RNA, Messenger; Sodium; Sodium, Dietary; Urination

The enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD2) provides mineralocorticoid receptor specificity for aldosterone by metabolizing glucocorticoids to their receptor-inactive 11-dehydro derivatives. The present study investigated the effects of the aldosterone receptor antagonists spironolactone and eplerenone on endothelial function in liquorice-induced hypertension. Glycyrrhizic acid (GA), a recognized inhibitor of 11beta-HSD2, was supplemented to the drinking water (3 g/L) of Wistar-Kyoto rats over a period of 21 days. From days 8 to 21, spironolactone (5.8+/-0.6 mg. kg(-1). d(-1)), eplerenone (182+/-13 mg. kg(-1). d(-1)), or placebo was added to the chow (n=7 animals per group). Endothelium-dependent or -independent vascular function was assessed as the relaxation of preconstricted aortic rings to acetylcholine or sodium nitroprusside, respectively. In addition, aortic endothelial nitric oxide synthase (eNOS) protein content, nitrate tissue levels, and endothelin-1 (ET-1) protein levels were determined. GA increased systolic blood pressure from 142+/-8 to 185+/-9 mm Hg (P<0.01). In the GA group, endothelium-dependent relaxation was impaired compared with that in controls (73+/-6% versus 99+/-5%), whereas endothelium-independent relaxation remained unchanged. In the aortas of 11beta-HSD2-deficient rats, eNOS protein content and nitrate tissue levels decreased (1114+/-128 versus 518+/-77 microgram/g protein, P<0.05). In contrast, aortic ET-1 protein levels were enhanced by GA (308+/-38 versus 497+/-47 pg/mg tissue, P<0.05). Both spironolactone and eplerenone normalized blood pressure in animals on GA (142+/-9 and 143+/-9 mm Hg, respectively, versus 189+/-8 mm Hg in the placebo group; P<0.01), restored endothelium-dependent relaxation (96+/-3% and 97+/-3%, respectively, P<0.01 versus placebo), blunted the decrease in vascular eNOS protein content and nitrate tissue levels, and normalized vascular ET-1 levels. This is the first study to demonstrate that aldosterone receptor antagonism normalizes blood pressure, prevents upregulation of vascular ET-1, restores NO-mediated endothelial dysfunction, and thus, may advance as a novel and specific therapeutic approach in 11beta-HSD2-deficient hypertension.

Topics: 11-beta-Hydroxysteroid Dehydrogenase Type 2; Animals; Aorta; Blood Pressure; Body Weight; Endothelin-1; Endothelium, Vascular; Enzyme Inhibitors; Eplerenone; Glycyrrhiza; Glycyrrhizic Acid; Heart Rate; Hydroxysteroid Dehydrogenases; Hypertension; In Vitro Techniques; Male; Mineralocorticoid Receptor Antagonists; Molecular Structure; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Plants, Medicinal; Rats; Rats, Inbred WKY; Spironolactone; Vasodilation

The combination of an angiotensin II receptor antagonist and a thiazide has been used extensively in the treatment of patients with overt heart failure. The effect of this combination on the vascular wall early in the disease, however, has not been investigated. To evaluate this effect, the vascular status of 3-month-old cardiomyopathic hamsters was assessed after daily administration of a combination of losartan (25 mg/kg, p.o.) and hydrochlorothiazide (6.5 mg/kg, p.o.) over an 8-week period. Age-matched golden hamsters were used as healthy controls. The contractile response of aortic rings to endothelin-1 was significantly higher in cardiomyopathic hamsters than in control animals. Concentration-response curves for the endothelin-1-induced contraction were displaced to the right after hydrochlorothiazide+losartan treatment (toward the curves for healthy controls); however, E(max) from treated hamsters was significantly reduced when compared to E(max) from untreated cardiomyopathic animals (1.016+/-0.073 vs. 1.346+/-0.153 g, P<0.05, n=6). No significant differences in the EC50 values from these curves were observed between hydrochlorothiazide+losartan treated and untreated cardiomyopathic animals (2.90+/-0.95 vs. 1.10+/-0.85 nM, P>0.05). The acetylcholine-induced relaxation observed in cardiomyopathic animals was not improved after treatment with hydrochlorothiazide+losartan or hydrochlorothiazide alone, but the combination of these drugs increased significantly the basal production of nitric oxide (NO). Angiotensin-converting enzyme activity increased in plasma (from 29.9+/-1.23 to 41.16+/-1.82 nmol x mg(-1) x min(-1), n=8, P<0.05) but decreased in the aorta (from 0.33+/-0.02 to 0.25+/-0.017 nmol x mg(-1) x min(-1), n=6, P<0.05) after treatment with hydrochlorothiazide+losartan. In addition, the combination of these drugs reduced the heart-to-body mass ratio (3.96+/-0.07 for treated vs. 5.01+/-0.20 mg/g for untreated animals, n=7, P<0.05), and the thickness of the aortic media (0.076+/-0.003 for treated vs. 0.149+/-0.009 mm for untreated animals, n=8, P<0.05). Although hydrochlorothiazide alone lowered systolic blood pressure to the same level achieved with both drugs in combination (from 166+/-10 for untreated cardiomyopathic animals to 84+/-1 mm Hg for hydrochlorothiazide+losartan, and 80+/-5 mm Hg for hydrochlorothiazide alone, P<0.05), no significant reduction in heart-to-body mass ratio was observed in animals treated with the diuretic alone (P>0.0

Topics: Acetylcholine; Animals; Antihypertensive Agents; Aorta, Thoracic; Body Weight; Cardiomyopathies; Cricetinae; Dose-Response Relationship, Drug; Drug Synergism; Endothelin-1; Endothelium, Vascular; Hydrochlorothiazide; In Vitro Techniques; Losartan; Male; Mesocricetus; Myocardium; Nitric Oxide; Organ Size; Peptidyl-Dipeptidase A; Vasoconstriction; Vasodilation; Vasodilator Agents

Increased endothelin-1 may be associated with elevation of blood pressure (BP) and promotion of vascular hypertrophy, especially in salt-sensitive hypertension. Mineralocorticoid hypertension has been associated with activation of the endothelin system. We evaluated whether in aldosterone-infused rats the selective endothelin type A receptor-antagonist BMS 182874 prevents BP elevation and vascular hypertrophy. Rats were infused with aldosterone (0.75 microg/h) subcutaneously via a mini-osmotic pump and were offered 1% NaCl in the drinking water+/-BMS 182874 (40 mg/kg in food) for 6 weeks. Systolic BP was monitored by the tail-cuff method, and vascular changes of mesenteric arteries were evaluated using a pressurized myograph. Aldosterone-infusion significantly increased BP to 151+/-7 mm Hg compared with controls (108+/-4 mm Hg, P<0.01). BMS 182874 normalized BP (117+/-4 mm Hg). Media cross-sectional area of aorta was significantly increased by aldosterone infusion (P<0.05), and BMS treatment normalized it (P<0.001). Aldosterone infusion increased media width and media-to-lumen ratio of mesenteric resistance arteries (17.6+/-0.4 microm and 7.5+/-0.4%) compared with controls (14.2+/-0.5 microm, P<0.01, and 5.9+/-0.1%, P<0.05). BMS 182874 normalized media and media-to-lumen ratio (15.1+/-0.6 microm and 5.7+/-0.1%, both P<0.01). In conclusion, the endothelin type A receptor antagonist attenuated BP elevation and prevented vascular remodeling or hypertrophy of aorta and mesenteric resistance arteries in aldosterone-infused rats. These results suggest a role for endothelin-1 in BP elevation and structural alterations of large and small vessels in aldosterone and salt-induced hypertension.

Topics: Aldosterone; Animals; Antihypertensive Agents; Aorta; Blood Pressure; Body Weight; Dansyl Compounds; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Hypertension; Hypertrophy; Infusions, Parenteral; Male; Mesenteric Arteries; Potassium; Protein Precursors; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; RNA, Messenger; Vasoconstriction; Vasodilation

The enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD) prevents inappropriate activation of the nonselective mineralocorticoid receptors by glucocorticoids. Renal activity of 11beta-HSD is decreased in patients with apparent mineralocorticoid excess (SAME), licorice-induced hypertension, and essential hypertension. Although expressed in vascular cells, the role of 11beta-HSD in the regulation of vascular tone remains to be determined.. lycyrrhizic acid (GA; 50 mg/kg IP, twice daily for 7 days) caused a significant inhibition of 11beta-HSD activity and induced hypertension in Wistar-Kyoto rats (157 versus 127 mm Hg in controls; P<0.01). After 11beta-HSD inhibition, aortic endothelial nitric oxide (NO) synthase (eNOS) protein content, nitrate tissue levels, and acetylcholine-induced release of NO were blunted (all P<0.05 versus controls). In contrast, vascular prepro-endothelin (ET)-1 gene expression, ET-1 protein levels, and vascular reactivity to ET-1 were enhanced by GA treatment (P<0.05 versus controls). Chronic ET(A) receptor blockade with LU135252 (50 mg. kg(-1). d(-1)) normalized blood pressure, ET-1 tissue content, vascular reactivity to ET-1, vascular eNOS protein content, and nitrate tissue levels and improved NO-mediated endothelial function in GA-treated rats (P<0.05 to 0.01 versus untreated and verapamil-treated controls). In human endothelial cells, GA increased production of ET-1 in the presence of corticosterone, which indicates that activation of the vascular ET-1 system by 11beta-HSD inhibition can occur independently of changes in blood pressure but is dependent on the presence of glucocorticoids.. Chronic ET(A) receptor blockade normalizes blood pressure, prevents upregulation of vascular ET-1, and improves endothelial dysfunction in 11beta-HSD inhibitor-induced hypertension and may emerge as a novel therapeutic approach in cardiovascular disease associated with reduced 11beta-HSD activity.

Topics: 11-beta-Hydroxysteroid Dehydrogenases; Acetylcholine; Animals; Blood Pressure; Body Weight; Cells, Cultured; Corticosterone; Dose-Response Relationship, Drug; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Endothelium, Vascular; Gene Expression Regulation; Glycyrrhizic Acid; Heart Rate; Humans; Hydroxysteroid Dehydrogenases; Hypertension; Male; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Norepinephrine; Phenylpropionates; Potassium Chloride; Protein Precursors; Pyrimidines; Rats; Rats, Inbred WKY; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; RNA, Messenger; Vascular Diseases; Vasoconstriction; Vasodilation; Vasodilator Agents; Verapamil

We evaluated the effects of cilnidipine, a long-acting Ca(2+) channel antagonist, on endothelial nitric oxide synthase (eNOS), preproendothelin-1 and endothelin ETA receptor expression in the left ventricle, and evaluated the relations between these effects and coronary microvascular remodeling and extracellular signal-regulated kinases belonging to one subfamily of mitogen-activated protein kinases in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Cilnidipine (DOCA-cilnidipine, 1 mg/kg/day, subdepressor dose) or vehicle (DOCA-vehicle) was given after induction of DOCA-salt hypertension for 5 weeks. The eNOS mRNA and protein expression in the left ventricle was significantly lower in DOCA-vehicle than in control rats and significantly higher in DOCA-cilnidipine than in DOCA-vehicle rats. Preproendothelin-1 and endothelin ETA receptor expression levels and phospho-p42/p44 extracellular signal-regulated kinase activities were significantly increased in DOCA-vehicle compared with control rats and significantly suppressed in DOCA-cilnidipine compared with DOCA-vehicle rats. DOCA-vehicle rats showed a significant increase in the wall-to-lumen ratio, perivascular fibrosis and myocardial fibrosis, with all these parameters being significantly improved by cilnidipine. These results led us to conclude that phospho-p42/p44 extracellular signal-regulated kinase activities may contribute to the coronary microvascular remodeling of DOCA rats and that protective effects of cilnidipine on cardiovascular remodeling may be at least in part mediated by an increased eNOS expression and a decreased endothelin-1 and endothelin ETA receptor expression in the left ventricle.

Topics: Animals; Blotting, Western; Body Weight; Calcium Channel Blockers; Coronary Vessels; Dihydropyridines; Endothelin-1; Endothelins; Gene Expression Regulation; Heart Ventricles; Hemodynamics; Hypertension; Male; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Organ Size; Protein Precursors; Rats; Rats, Wistar; Receptor, Endothelin A; Receptors, Endothelin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

We investigated the potential of natural occurring antioxidant alpha-lipoic acid to prevent hypertension and hypertensive tissue injury induced by deoxycorticosterone acetate (DOCA) and salt in rats. Two weeks after the start of DOCA-salt treatment, the rats were given alpha-lipoic acid (10 or 100 mg/kg/day, s.c.) or its vehicle for 2 weeks. Uninephrectomized rats without DOCA-salt treatment served as sham-operated controls. In vehicle-treated DOCA-salt rats, systolic blood pressure increased markedly after 3-4 weeks. Daily administration of 100 mg/kg alpha-lipoic acid for 2 weeks suppressed the increase in systolic blood pressure, whereas 10 mg/kg alpha-lipoic acid did not affect the progression of DOCA-salt-induced hypertension. When the degree of vascular hypertrophy of the aorta was morphometrically evaluated at 4 weeks, there were significant increases in media cross-sectional area in vehicle-treated DOCA-salt rats compared with sham-operated rats. The development of vascular hypertrophy was markedly suppressed by alpha-lipoic acid at 100 mg/kg but not at 10 mg/kg. Histopathological examination of the kidney in vehicle-treated DOCA-salt rats revealed fibrinoid-like necrosis in glomeruli and thickening of small arteries. In these animals, creatinine clearance decreased, and fractional excretion of Na(+), urinary excretion of protein and N-acetyl-beta-glucosaminidase increased. Such renal lesions and dysfunctions were ameliorated in DOCA-salt rats given alpha-lipoic acid. In addition, a marked increase in endothelin-1 content in both the aorta and kidney was evident in vehicle-treated DOCA-salt rats compared with findings in sham-operated rats. Significant attenuation of this increase occurred in alpha-lipoic acid-treated DOCA-salt rats. These results suggest that administration of alpha-lipoic acid to DOCA-salt hypertensive rats lessens the increased blood pressure and protects against renal and vascular injuries, possibly through the suppression of renal and vascular endothelin-1 overproduction.

Topics: Animals; Aorta; Blood Pressure; Body Weight; Desoxycorticosterone; Dose-Response Relationship, Drug; Endothelin-1; Hypertension; Hypertrophy; Kidney; Kidney Diseases; Male; Organ Size; Rats; Rats, Sprague-Dawley; Thioctic Acid

Vascular endothelial cells produce nitric oxide (NO), which is a potent vasodilator substance and has been proposed as having antiatherosclerotic property. Vascular endothelial cells also produce endothelin-1 (ET-1), which is a potent vasoconstrictor peptide and has potent proliferating activity on vascular smooth muscle cells. Therefore, ET-1 has been implicated in the progression of atheromatous vascular disease. Because exercise training has been reported to produce an alteration in the function of vascular endothelial cells in animals, we hypothesized that exercise training influences the production of NO and ET-1 in humans. The purpose of the present study was to examine whether chronic exercise could influence the plasma levels of NO (measured as the stable end product of NO, i.e., nitrite/nitrate [NOx]) and ET-1 in humans. Eight healthy young subjects (20.3 +/- 0.5 yr old) participated in the study and exercised by cycling on a leg ergometer (70% VO2max for 1 hour, 3-4 days/week) for 8 weeks. Venous plasma concentrations of NOx and ET-1 were measured before and after (immediately before the end of 8-week exercise training) the exercise training, and also after the 4th and 8th week after the cessation of training. The VO2max significantly increased after exercise training. After the exercise training, the plasma concentration of NOx significantly increased (30.69 +/- 3.20 vs. 48.64 +/- 8.16 micromol/L, p < 0.05), and the plasma concentration of ET-1 significantly decreased (1.65 +/- 0.14 vs. 1.23 +/- 0.12 pg/mL, p < 0.05). The increase in NOx level and the decrease in ET-1 level lasted to the 4th week after the cessation of exercise training and these levels (levels of NOx and ET-1) returned to the basal levels (the levels before the exercise training) in the 8th week after the cessation of exercise training. There was a significant negative correlation between plasma NOx concentration and plasma ET-1 concentration. The present study suggests that chronic exercise causes an increase in production of NO and a decrease in production of ET-1 in humans, which may produce beneficial effects (i.e., vasodilative and antiatherosclerotic) on the cardiovascular system.

Topics: Adult; Body Composition; Body Weight; Endothelin-1; Endothelium, Vascular; Exercise; Exercise Test; Hemodynamics; Humans; Male; Nitric Oxide; Oxygen Consumption

Polymorphism of the dopamine receptor type-2 (D(2)) gene is associated with essential hypertension. To assess whether D(2) receptors participate in regulation of blood pressure (BP), we studied mice in which the D(2) receptor was disrupted. In anesthetized mice, systolic and diastolic BPs (in millimeters of mercury) were higher in D(2) homozygous and heterozygous mutant mice than in D(2)+/+ littermates. BP after alpha-adrenergic blockade decreased to a greater extent in D(2)-/- mice than in D(2)+/+ mice. Epinephrine excretion was greater in D(2)-/- mice than in D(2)+/+ mice, and acute adrenalectomy decreased BP to a similar level in D(2)-/- and D(2)+/+ mice. An endothelin B (ET[B]) receptor blocker for both ET(B1) and ET(B2) receptors decreased, whereas a selective ET(B1) blocker increased, BP in D(2)-/- mice but not D(2)+/+ mice. ET(B) receptor expression was greater in D(2)-/- mice than in D(2)+/+ mice. In contrast, blockade of ET(A) and V(1) vasopressin receptors had no effect on BP in either D(2)-/- or D(2)+/+ mice. The hypotensive effect of an AT(1) antagonist was also similar in D(2)-/- and D(2)+/+ mice. Basal Na(+),K(+)-ATPase activities in renal cortex and medulla were higher in D(2)+/+ mice than in D(2)-/- mice. Urine flow and sodium excretion were higher in D(2)-/- mice than in D(2)+/+ mice before and after acute saline loading. Thus, complete loss of the D(2) receptor results in hypertension that is not due to impairment of sodium excretion. Instead, enhanced vascular reactivity in the D(2) mutant mice may be caused by increased sympathetic and ET(B) receptor activities.

Topics: Adrenergic alpha-Antagonists; Angiotensin Receptor Antagonists; Animals; Antidiuretic Hormone Receptor Antagonists; Antihypertensive Agents; Blood Pressure; Body Weight; Catechols; Endothelin Receptor Antagonists; Endothelin-1; Female; Genotype; Hypertension; Losartan; Male; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Mice, Knockout; Oligopeptides; Phentolamine; Piperidines; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Adrenergic; Receptors, Dopamine D2; Receptors, Endothelin; Sodium; Sodium-Potassium-Exchanging ATPase; Urodynamics; Viper Venoms

We previously demonstrated a differential activation of the endothelin-1 (ET-1) pathway in male and female deoxycorticosterone (DOCA)-salt hypertensive rats, with the male rats exhibiting marked alterations in vascular and pressor responses to ET-1 and Suc-[Glu,(9)Ala(11,15)]-ET-1(8-21) (IRL-1620), an ET(B) agonist. Mechanisms underlying these gender differences are unclear, and we hypothesized that the ovarian hormones attenuate vascular ET(B) responses in female DOCA-salt rats. Female Wistar rats were randomized in 3 groups: sham-operated, ovariectomized (OVX), and OVX plus hormone replacement with estradiol (E) or estradiol/progesterone (EP). Two weeks later, rats were uninephrectomized and further randomized in DOCA-salt (subcutaneous injections of desoxycorticosterone and drinking water containing NaCl/KCl) and control normotensive (subcutaneous injections of vehicle and tap water). Blood pressure was evaluated both by direct and standard tail-cuff methods. Responses to IRL-1620 were evaluated in vivo/in situ in the mesenteric microcirculation. mRNA expression of ET-1 and ET(A/B) receptors was evaluated in mesenteric arteries by reverse transcription-polymerase chain reaction and expressed relative to GAPDH. OVX-DOCA rats developed a more severe form of hypertension than did DOCA rats. Treatment with E or EP restored blood pressure to levels observed in DOCA rats. In the mesentery, IRL-1620 induced vasodilatation in control rats, a mild vasoconstriction in DOCA rats, and marked vasoconstriction in OVX-DOCA rats. Both E and EP decreased IRL-1620-induced vasoconstriction in the DOCA group. In the normotensive group, OVX did not change blood pressure or IRL-1620-induced vasodilation. Removal of the ovaries increased ET-1 mRNA in arteries from DOCA and control rats, although treatment with E or EP reversed these changes. Vascular ET(B) receptor mRNA levels were greatly enhanced in OVX-DOCA but not OVX-control rats. Hormone replacement with E or EP restored ET(B) receptor expression in the DOCA group. A greater blood pressure-lowering effect of bosentan (ET(A)/ET(B) blocker) was observed in OVX-DOCA rats. The observation that OVX worsens hypertension as well as the altered ET(B) receptor-mediated responses and the effects of bosentan in female DOCA rats supports our suggestion that the ovarian hormones modulate ET-1/ET(B) receptor vascular responses/expression in DOCA-salt hypertension.

Topics: Animals; Blood Pressure; Body Weight; Desoxycorticosterone; Endothelin-1; Endothelins; Estradiol; Female; Hypertension; In Vitro Techniques; Mesenteric Arteries; Organ Size; Ovariectomy; Peptide Fragments; Potassium, Dietary; Progesterone; Rats; Rats, Wistar; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sodium Chloride, Dietary; Time Factors; Uterus; Vasoconstriction

We compared agonist-evoked responses in the perfused mesenteric vascular bed (MVB) of streptozotocin (STZ) diabetic Sprague-Dawley rats 2 and 14 weeks after induction of diabetes. Endothelin-1 (ET-1)-, methoxamine (MTX)-, and KCl-evoked vasoconstrictor responses were unchanged in 2-week-old diabetic rats. In contrast, both the sensitivity (P < 0.01) and the maximal vasoconstrictor responses (P < 0.05) to ET-1 were attenuated in 14-week-old diabetic rats, whereas endothelin plasma levels were increased (P < 0.05). Although no differences were observed in responses to KCl in either the 2- or 14-week-old diabetic groups, MTX-evoked maximal responses were attenuated in the 14-week-old group (P < 0.01). Changes in agonist-evoked responses in the 14-week-old diabetic group were unaffected by the protein kinase C (PKC) inhibitor, staurosporine, the phospholipase C (PLC) inhibitor, U73122, the calcium channel blocker, nifedipine, the calcium pump inhibitor, cyclopiazonic acid (CPA), or by endothelial denudation. Sodium fluoride (NaF), an activator of guanosine triphosphate binding proteins (G proteins) normalized the responses in the 14-week-old diabetic group. These data suggest that advanced stages of STZ are associated with alterations in G protein receptor coupling and/or activity leading to the attenuation of responses to vasoconstrictor agonists.

Topics: Animals; Blood Glucose; Body Weight; Calcium Channel Blockers; Diabetes Mellitus, Experimental; Endothelin-1; Enzyme Inhibitors; Estrenes; In Vitro Techniques; Indoles; Male; Mesenteric Arteries; Methoxamine; Nifedipine; Perfusion; Phosphatidylinositols; Potassium Chloride; Protein Kinase C; Pyrrolidinones; Rats; Rats, Sprague-Dawley; Sodium Fluoride; Staurosporine; Streptozocin; Type C Phospholipases; Vasoconstriction; Vasoconstrictor Agents

To evaluate the effect of age and body weight on several neurohumoral variables that are commonly altered in heart failure in Cavalier King Charles Spaniels.. 17 healthy privately owned Cavalier King Charles Spaniels, 10 males and 7 females, ranging in age from 0.4 to 9.7 years, and ranging in body weight from 6.6 to 12.2 kg.. The clinical condition of the dogs was evaluated by physical examination, thoracic radiography, and echocardiography. Plasma nitrate and nitrite (P-NN), N-terminal atrial natriuretic and brain natriuretic peptides (NT-ANP and BNP, respectively), endothelin (ET-1), urine cyclic guanosine monophosphate (U-cGMP), and urine nitrate and nitrite (U-NN) concentrations were analyzed.. Plasma concentrations of NT-ANP and P-NN increased significantly with age, but plasma NT-ANP and P-NN also correlated significantly, irrespective of age. A modest increase of left atrial size did not explain the increase of NT-ANP and P-NN with age. Concentration of ET-1 correlated positively with heart rate; heart rate did not change with age. Weight had a negative impact on NT-ANP, P-NN, and U-cGMP concentrations and left atrial relative size.. Age-matched controls are essential for evaluation of NT-ANP and P-NN concentrations and left atrial size. Weight may alter reference values of plasma NT-ANP, P-NN, and urine cGMP concentrations. Natriuretic peptides can be used as further evidence that heart failure exists. The increased plasma concentrations of NT-ANP (but not BNP) and P-NN with aging reflect neurohumoral physiologic changes that must be distinguished from pathologic changes in patients with heart failure.

Topics: Age Factors; Animals; Atrial Natriuretic Factor; Body Weight; Cardiac Output; Creatinine; Cyclic GMP; Dogs; Echocardiography; Electrocardiography; Endothelin-1; Female; Heart Failure; Heart Rate; Male; Natriuretic Peptide, Brain; Neurotransmitter Agents; Nitrites; Radiography, Thoracic; Regression Analysis

Cardiac endothelin-1 (ET-1) levels and ET receptor expression are increased in congestive heart failure (CHF). In order to determine whether this results in increased responsiveness of ET-A or ET-B receptors to ET-1, we evaluated the contractile effects of ET-1 in isolated papillary muscles isolated from hearts of control rats and from rats 4 weeks post myocardial infarction (MI) having received no therapy or chronic quinapril therapy. The ET-1 dose-response was biphasic in normal muscles. The use of the selective ET-A receptor antagonist BQ123 and the selective ET-B receptor antagonist BQ788 revealed that the initial decrease in tension was the result of ET-B receptor stimulation. Blockade of nitric oxide (NO) production with L-NAME abolished the initial decrease in tension. MI resulted in CHF that was partially reversed by quinapril. In MI, the positive inotropic effects of ET-1 were enhanced due to the loss of the initial ET-B receptor mediated decrease in tension, as well as an increase in the positive inotropic effects of ET-A receptors. This was associated with an increase in ET-A and ET-B receptor mRNA and a decrease in cardiac ecNOS protein. Four weeks of therapy with quinapril attenuated the positive inotropic effects of ET-1 and prevented the increase in ET-A receptor mRNA. Although quinapril did not restore the effects of ET-B receptor stimulation or prevent the increase in ET-B mRNA, it did restore cardiac ecNOS protein expression. Thus, the inotropic response to ET-1 is biphasic due to an overall positive inotropic effect of ET-A receptor stimulation and an ET-B receptor mediated decrease in contractility at low ET-1 concentrations which appears to be mediated by cardiac ecNOS (NO). In post-MI CHF, responsiveness to ET-A receptors increases and the ET-B mediated negative inotropic response is lost despite an increase in both receptor subtypes. Quinapril therapy attenuates these effects and normalises cardiac ecNOS protein.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Binding, Competitive; Body Weight; Dose-Response Relationship, Drug; Endothelin-1; Endothelium, Vascular; Heart Failure; Hemodynamics; Isoquinolines; Kinetics; Male; Muscles; Myocardial Contraction; Myocardial Infarction; Myocardium; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Oligopeptides; Organ Culture Techniques; Organ Size; Papillary Muscles; Peptides, Cyclic; Piperidines; Protein Binding; Quinapril; Rats; Rats, Wistar; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tetrahydroisoquinolines; Time Factors; Vasoconstrictor Agents; Viper Venoms

Recently, an endothelin (ET-1) with a potent vasoconstrictive activity and stimulative activity of vascular muscular cell growth was discovered and blood ET-1 levels were higher in diabetic patients than in healthy subjects, suggesting that high ET-1 levels assist development and progression of diabetic microangiography.. We examined renal function, and serum and tissue ET-1 levels in streptozotocin (STZ)-induced diabetic rats treated with a prostaglandin (PG) I(2) derivative to investigate the effect of PGI(2) in diabetic vascular disturbance.. Renal weight, urinary albumin, urinary N-acetyl-beta,D-glucosaminidase (NAG) and serum ET-1 levels increased in STZ-induced diabetic rats, and a tendency to increase in renal tissue ET-1 levels was observed. Furthermore, electron-microscopic findings in the kidneys showed mesangial cell proliferation and mesangial matrix expansion which might be caused by diabetic nephropathy. The PGI(2) derivative reduced urinary albumin and NAG levels in STZ-induced rats. It was considered, therefore, that the PGI(2) derivative is effective in diabetic nephropathy. As the PGI(2) derivative also reduced renal tissue ET-1 levels, improvement of diabetic nephropathy partially was considered to result from the reduction of renal tissue ET-1 levels.. In STZ-induced rats, increased serum ET-1 levels and a tendency to increase in renal tissue ET-1 levels were associated with increases in urinary albumin and NAG levels, and these levels were decreased by a PGI(2) derivative. These findings suggested that increased ET-1 concentrations assist development and progression of diabetic nephropathy, especially diabetic microangiopathy, and the PGI(2) derivative may be effective for inhibition of diabetic microangiopathy mediated by reduction of ET-1 concentrations.

Topics: Albuminuria; Animals; Blood Glucose; Body Weight; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Endothelin-1; Epoprostenol; Fasting; Hypoglycemic Agents; Kidney; Male; Microscopy, Electron; Organ Size; Rats

In a previous paper we gave evidence that chronic oral defibrotide antagonizes the noxious effect of developing atherosclerosis in the cardiovascular system. In the present paper we give evidence that defibrotide is still capable of exerting beneficial effects on cardiovascular function once atherosclerosis is established. In fact, there was statistically significant amelioration by defibrotide infusion in the following, all of which were hampered by established atherosclerosis: in rabbit aorta relaxation to acetylcholine, prostaglandin E2, and 6-keto-prostaglandin F1alpha generation from rabbit aortas, rabbit heart left ventricular end-diastolic pressure, coronary perfusion pressure, and left ventricular developed pressure, vasopressor activity of acetylcholine and endothelin-1 on coronary perfusion pressure, and 6-keto-prostaglandin F1alpha generation from the rabbit heart. Since prostacyclin takes part in NO generation, is cellular protective, and inhibits 5-lipoxygenase product synthesis, its increase, caused by defibrotide, could explain defibrotide cardioprotective activity. Prostacyclin activity could be backed by prostaglandin E2, another cardioprotective prostaglandin.

Topics: 6-Ketoprostaglandin F1 alpha; Acetylcholine; Animals; Aorta; Arteriosclerosis; Blood Pressure; Body Weight; Cardiovascular Physiological Phenomena; Cholesterol, Dietary; Dinoprostone; Endothelin-1; Fibrinolytic Agents; Heart; In Vitro Techniques; Lipids; Male; Muscle Contraction; Muscle, Smooth, Vascular; Organ Size; Platelet Aggregation Inhibitors; Polydeoxyribonucleotides; Rabbits; Reperfusion; Ventricular Function, Left

Endothelium-derived factors modulate tone and may be involved in hyporeactivity to vasoconstrictors, such as norepinephrine or angiotensin II, as has been previously described during gestation. The endothelium produces endothelin-1, a major vasoconstrictor peptide, therefore aortic contractions to endothelin-1 (10(-10) to 3 x 10(-7) M) were used to assess the role of the endothelium in pregnant Wistar rats (at 20 days of gestation). Late pregnancy is characterized by a significantly diminished systolic blood pressure in conscious rats (-17 mmHg, P < 0.001, n = 14). In pregnant and in age-matched nonpregnant female rats, endothelin-1 induced aortic contraction was greater when endothelium was present (at least P < 0.01). Indomethacin significantly reduced this contraction in aortic rings with intact endothelium in all groups. In aortic rings that had endothelium physically removed, contraction to endothelin-1 was greater in pregnant rats than in nonpregnant ones. Indomethacin decreased contraction of aortic rings in pregnant rats only. These results suggest an enhanced synthesis of vasoconstrictors by cyclooxygenases in vascular smooth muscle during pregnancy. In vessels with intact endothelium, we did not find hyporeactivity to endothelin-1 during late pregnancy. Contraction to endothelin-1 involved ET(A) receptors because it was decreased by BQ-123, an ET(A) receptor antagonist, whereas there was no significant change when using BQ-788, an ET(B) receptor antagonist.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Aorta, Thoracic; Blood Pressure; Body Weight; Endothelin Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Enzyme Inhibitors; Female; In Vitro Techniques; Indomethacin; Male; Muscle Contraction; Muscle, Smooth, Vascular; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Oligopeptides; Peptides, Cyclic; Piperidines; Pregnancy; Pregnancy, Animal; Rats; Rats, Wistar; Receptors, Endothelin; Viper Venoms

To investigate the role of renal endothelin-1 (ET-1) synthesis in water-sodium homeostasis, we measured mRNA expressions, protein levels, enzyme activity, and receptor binding of the renal ET-1 system in a DOCA- and salt-treated rat model. Male Wistar rats were divided into control and DOCA- and salt-treated (DOCA-Salt) groups. The DOCA-Salt group received 25 mg/kg body wt DOCA and was maintained on 1% NaCl drinking water. Rats were killed on days 1, 2, 4, and 10 of the experiment. Urinary ET-1-like immunoreactivity significantly increased from the second day in the DOCA-Salt group and correlated well with the urinary sodium excretion rate (r = 0.81, P < 0.001). Renal endothelin-converting enzyme (ECE) activity, ET-1, and ECE-1 mRNA expressions were significantly increased in the renal medullary area of DOCA-Salt rats. In situ hybridization and immunohistochemical studies showed that the increase in ET-1 synthesis was mainly localized in the inner medullary collecting ducts. The maximum binding of endothelin B receptor also increased from the second day in the renal medulla of the DOCA-Salt group. Our results suggest that renal medullary synthesized ET-1 may be a natriuretic factor and may participate in the intrarenal regulation of water and salt homeostasis in prehypertensive DOCA-and salt-treated rats.

Topics: Animals; Aorta; Aspartic Acid Endopeptidases; Blood Pressure; Body Weight; Desoxycorticosterone; Disease Models, Animal; Endothelin-1; Endothelin-Converting Enzymes; Hypertension; Immunohistochemistry; In Situ Hybridization; Kidney Medulla; Male; Metalloendopeptidases; Organ Size; Rats; Rats, Wistar; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Renin; RNA, Messenger; Sodium Chloride, Dietary; Water-Electrolyte Balance

The Donryu rat is resistant to a high cholesterol diet in that typical atheromatous lesions do not develop. Using electron microscopic immunocytochemical techniques, the effects of a CCT diet (4% cholesterol with 1% cholic acid and 0.5% thiouracil) on the distributions of neuronal, macrophage, and endothelial specific nitric oxide synthase (NOS I, NOS II, and NOS III) and endothelin-1 (ET-1) immunoreactivity were examined in the thoracic aortic intima. Atheromatous lesions were absent, but immunocytochemistry showed 1. 4+/-0.52% and 4.0+/-0.9% endothelial cells (EC) with positive staining for NOS I and NOS III, respectively, compared with 16.3+/-2. 5% and 88.6+/-2.48% in control Donryu rats. The CCT-supplemented diet induced expression of NOS II immunoreactivity in thoracic aortic intimal cells. EC, subendothelial macrophages, and smooth muscle cells (SMC) also showed high NOS II-positive staining. The percentage of NOS II-immunoreactive EC was 43+/-1.8%. In control groups, no NOS II immunoreactive cells were observed. The percentage of ET-1 immunopositive cells was also significantly increased by 9. 2+/-0.66% and 64.2+/-1.4% in control and CCT-fed groups, respectively. It is concluded that the administration of a high cholesterol diet in Donryu rats produces endothelial dysfunction associated with changes in the balance of the different isoforms of NOS and ET-1. Therefore, the increase in inducible NOS and ET-1 immunoreactivity seen during the cholesterol-enriched diet appears to be a compensatory reaction of aortic wall cells to the high cholesterol supplementation.

Topics: Animals; Aorta; Body Weight; Cholesterol, Dietary; Cholic Acid; Diet; Endothelin-1; Endothelium, Vascular; Immunohistochemistry; Lipids; Male; Microscopy, Electron; Microscopy, Electron, Scanning; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Rats; Rats, Inbred Strains; Thiouracil

Streptozotocin (STZ)-induced diabetes causes an upregulation in the expression of endothelin (ET) receptors in the rat prostate (Eur J Pharmacol 310:197, 1996). We examined the effects of insulin treatment, started 8 weeks after the induction of diabetes, on the expression and distribution of ET receptors and their respective mRNAs in the rat prostate. The densities, pharmacological properties and distribution of ET receptors in the rat prostate were examined using radioligand receptor binding and autoradiographic studies, and gene expression of ET receptors was evaluated utilizing the reverse transcription-polymerase chain reaction (RT-PCR). STZ-injected rats had smaller prostates and reduced serum testosterone levels than control and insulin treated diabetic animals. ET receptor density was shown to be significantly higher in the prostate from diabetic rats than those from either control or insulin treated diabetic animals. The pharmacological profile of prostatic ET receptors was similar in all groups (approximately 80% ET(A); 20% ET(B) subtype). ET receptors were predominantly localized to the prostatic stroma. Induction of diabetes increased the expression of mRNA levels of ET(A) and ET receptors, and insulin treatment reversed this upregulation to control levels. These results indicate that (1) ET receptor subtypes are expressed in the rat prostate as transcription and translation products; (2) insulin can normalize the diabetes-induced upregulation in the expression of ET receptors and their respective mRNAs; and (3) diabetes-induced regression of the prostate may involve an alteration in ET receptors.

Topics: Animals; Autoradiography; Blood Glucose; Body Weight; Diabetes Mellitus, Experimental; Endothelin Receptor Antagonists; Endothelin-1; Insulin; Iodine Radioisotopes; Male; Organ Size; Prostate; Protein Isoforms; Radioligand Assay; Random Allocation; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Testosterone; Up-Regulation

Mesangial cell hypertrophy and increased extracellular matrix (ECM) contribute to mesangial expansion in early progressive diabetic nephropathy. Previous studies suggest that the growth factor endothelin-1 (ET-1) is not only up-regulated in diabetes, but may mediate the effects of hyperglycemia on mesangial cell hypertrophy and ECM synthesis. In models of diabetes mellitus, the mechanisms underlying increased ET-1 peptide and mRNA remain unknown. Therefore, our purpose is to determine whether ET-1 gene activity increases in kidneys of streptozotocin (SZT)-treated rats.. Male Sprague-Dawley rats were injected with either SZT or vehicle. Parameters including glucose, body weight, 24-hour urine volume, urinary protein, and urinary ET-1 excretion were recorded. All rats were sacrificed at 12 weeks postinjection. Prepro-ET-1 mRNA from whole kidneys was determined using both RNase protection and reverse transcription-polymerase chain reaction (RT-PCR). The abundance of ET-1 peptide in primary cultured mesangial cells was detected by indirect immunofluorescence following treatment with 5.6, 11.2, or 22.5 mmol/L D-glucose for 24 hours. Cellular ET-1 mRNA was measured using RT-PCR in control cells at time 0 and also following exposure to increasing concentrations of glucose for 24 hours. Rat mesangial cells were transfected with a luciferase reporter construct containing the rat ET-1 promoter (pET1. Luc), and relative ET-1 promoter activity was measured after a 24-hour exposure to 5.6 and 22.5 mmol/L of D- or L-glucose.. After 12 weeks of hyperglycemia, diabetic rats gained less weight (344 +/- 23.9 vs. 548.75 +/- 15.08 g), had increased urinary volume (158.6 +/- 24.32 vs. 8.38 +/- 1.56 mL/day), and had marked proteinuria (101.7 +/- 12.2 vs. 14.1 +/- 2.8 mg/day) compared with controls. Total urinary ET-1 peptide increased 26.4-fold in diabetic versus control rats (17.5083 +/- 5.405 vs. 0.6635 +/- 0.343 ng/day). ET-1 mRNA extracted from whole rat kidneys was increased 2.1-fold in diabetic versus control animals. Primary cultured rat mesangial cells demonstrated a significant increase in immunofluorescence labeling of ET-1 peptide and ET-1 mRNA in response to increasing concentrations of glucose. Furthermore, transfected mesangial cells exposed to 22.5 mmol/L D-glucose showed a 1.6-fold increase in ET-1 promoter activity relative to those treated with 5.6 mmol/L glucose.. Glucose increases ET-1 gene expression in the kidney of the SZT-treated rat model of diabetes mellitus. Furthermore, high glucose induces ET-1 expression in primary cultured rat mesangial cells and directly enhances ET-1 promoter activity. The greater relative increase in peptide compared with transcription suggests the potential participation of other mechanisms such as increased mRNA stability, protein stability, and/or enhanced translational efficiency.

Topics: Animals; Blood Glucose; Body Weight; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Endothelin-1; Endothelins; Extracellular Matrix; Gene Expression; Glomerular Mesangium; Glucose; Hyperglycemia; Male; Promoter Regions, Genetic; Protein Precursors; Proteinuria; Rats; Rats, Sprague-Dawley; RNA, Messenger; Transcription, Genetic; Transfection; Urine; Vasoconstriction

The renin-angiotensin system and endothelin are important regulators of the cardiovascular system. Although increased production of endothelin-1 (ET-1) is reported in patients with heart failure, the detailed mechanism remains to be determined. To elucidate the relationship between the renin-angiotensin system and ET-1 in hypertensive heart failure, we evaluated the effects of long-term treatment with imidapril, an angiotensin converting enzyme (ACE) inhibitor, on preproET-1, endothelin A receptor (ETAR), and ACE mRNA expression in the left ventricle and evaluated these in relation to myocardial remodeling in the failing heart of Dahl salt-sensitive (DS) hypertensive rats fed a high salt diet. In DS rats fed an 8% NaCl diet after the age of 6 weeks, a stage of concentric left ventricular hypertrophy at 11 weeks (DSLVH) was followed by a distinct stage of left ventricular failure with chamber dilatation at 18 weeks (DSHF). Imidapril (DSHF-IM, n = 8, 1 mg/kg/day, subdepressor dose) or vehicle (DSHF-V, n = 8) was given from stage DSLVH to DSHF for 7 weeks, and age-matched (18 weeks) Dahl salt-resistant rats fed the same diet served as the control group (DR-C, n = 8). In both groups, blood pressure was similar and significantly higher than in DR-C. Markedly increased left ventricular end-diastolic diameter and reduced fractional shortening in DSHF-V was significantly ameliorated in DSHF-IM using transthoracic echocardiography. The preproET-1, ETAR, and ACE mRNA levels in the left ventricle were significantly increased in DSHF-V compared with DR-C, and significantly suppressed in DSHF-IM compared with DSHF-V. DSHF-V demonstrated a significant increase in the wall-to-lumen ratio and perivascular fibrosis in coronary arterioles, and myocardial fibrosis, with all these parameters being significantly improved by imidapril. In conclusion, myocardial remodeling and heart failure in DS rats fed a high salt diet were significantly ameliorated by a subdepressor dose of imidapril, which may be attributable to a decrease in ET-1 mRNA expression and angiotensin II in the left ventricle.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Body Weight; Cardiac Output, Low; Endothelin-1; Endothelins; Gene Expression; Heart Ventricles; Hemodynamics; Hypertension; Imidazoles; Imidazolidines; Male; Myocardial Contraction; Myocardium; Organ Size; Peptidyl-Dipeptidase A; Protein Precursors; Rats; Rats, Inbred Dahl; Receptor, Endothelin A; Receptors, Endothelin; RNA, Messenger; Ventricular Remodeling

Although evidence has been accumulated to support a role of endothelin-1 (ET-1) in cardiac hypertrophy, details of the pathophysiological significance of ET-1 in cardiac hypertrophy remain to be elucidated. In the present study, we investigated the effects of the vasodilator hydralazine on the blood pressure, cardiac hypertrophy and ET-1 gene expression in various tissues of spontaneously hypertensive rats (SHR-SP/Izm). Hydralazine (20 mg/kg/day) was administered orally from the age of 4 weeks for 8 weeks. Tissues of the kidney, heart, aorta and brain were obtained at the age of 12 weeks. Tissue expression of ET-1 mRNA was determined by reverse transcriptase polymerase chain reaction (RT-PCR) followed by Southern blot analysis. Administration of hydralazine resulted in a significant decrease in the blood pressure (156 +/- 1 mmHg vs 212 +/- 4 mmHg in controls) and an increase in the heart rate (470 +/- 20 bpm vs 402 +/- 23 bpm in controls). ET-1 mRNA expression was significantly decreased in the heart (x 1/2), kidney (x 1/4) and brain (x 1/2). There was no significant change of the cardiac weight (309 +/- 4 mg/100 g body weight vs 307 +/- 5 mg/100 g body weight in controls). The dissociation between ET-1 mRNA expression and cardiac hypertrophy in hydralazine-treated rats may suggest that the increased tissue ET-1 is not an indispensable factor of cardiac hypertrophy in hypertension. Sympathetic activation, as shown by the reactive tachycardia, may overcome the effects on the blood pressure and ET-1 expression.

Topics: Animals; Antihypertensive Agents; Blood Pressure; Body Weight; Cardiomegaly; Endothelin-1; Hydralazine; Male; Organ Size; Rats; Rats, Inbred SHR; RNA, Messenger

Using the orally active endothelin-A- (ET(A)) receptor antagonist LU135252, we determined whether endothelin-1 (ET-1) and/or dietary fat may be involved in angiotensin-converting enzyme (ACE) regulation in vivo. In C57BL6/J mice, renal and pulmonary tissue ACE activity (nmol/l His-Leu/mg protein) was measured and ACE mRNA expression, tissue ET-1 protein content and nitrite/nitrate level were measured in the kidney. Western-type diet increased renal ACE activity by 70% (55 +/- 4 vs 33 +/- 3 nmol/l His-Leu/mg protein, p < 0.05) and increased renal ET-1 levels (267 +/- 19 pg/g vs 190 +/- 18, p < 0.05). Chronic LU135252 treatment completely prevented activation of renal ACE activity (13.3 +/- 0.3 His-Leu/mg protein nmol/l, p < 0.05) independent of ACE mRNA expression or renal ET-1 protein levels. Thus, dietary fat activates renal ACE activity and ET-1 is involved in regulation of tissue ACE activity in vivo independently of ACE mRNA expression.

Topics: Animals; Body Weight; Dietary Fats; Endothelin-1; Kidney; Lipids; Male; Mice; Mice, Inbred C57BL; Nitrates; Nitrites; Peptidyl-Dipeptidase A; Receptor, Endothelin A; Receptors, Endothelin; Reverse Transcriptase Polymerase Chain Reaction

Cyclosporine (CsA) (45 mg/kg/day for 7 days) administration in female Wistar rats induced significant decrease in creatinine clearance (Ccr) and body weight loss (BWL). Urine volume (V) was not altered and proteinuria (PU) not provoked. These changes were associated with increased urinary endothelin 1 (ET-1) and thromboxane B(2)(TXB(2)) concentrations, and decreased urinary ratios of prostaglandin (6ketoPGF(1 alpha)and PGE(2)) to TXB(2)excretions. Nifedipine (NFD) (0.1 mg/kg/day for 7 days), a calcium channel blocker, administrated in addition to CsA, to another group of animals, significantly augmented Ccr and urine V but did not prevent BWL in comparison to CsA-only treated rats. The urinary ET-1 and TXB(2)concentrations displayed significant and non-significant decrease respectively, while the urinary excretion ratios of 6ketoPGF(1 alpha)/TXB(2)and PGE(2)/TXB(2)were significantly enhanced.These observations indicate that the partial protection of NFD in CsA-induced nephrotoxicity could be attributed to augmented urinary prostanoid ratios of renal vasodilators (6ketoPGF(1 alpha)and PGE(2)) to vasoconstrictor (TXB(2)) excretions, and also to reduced release of rather renal origin ET-1, the most potent mamalian vasoconstrictor peptide known to date. In a previous study, we found that NFD only slightly prevented structural renal damage, induced by CsA. So, the NFD protection refers only to functional toxicity and not to structural damage, mediated at least in part by the preservation of relatively high renal TXB(2)levels. However, other nephrotoxic factors and additional mechanisms could also be implicated in this CsA-induced syndrome.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Body Weight; Calcium Channel Blockers; Creatinine; Cyclosporine; Dinoprostone; Dose-Response Relationship, Drug; Endothelin-1; Endothelins; Enzyme Inhibitors; Female; Immunoassay; Kidney; Nifedipine; Proteinuria; Rats; Rats, Wistar; Spectrophotometry; Thromboxane B2; Urine

Endothelin (ET)-1 plays an important role in the pathogenesis of deoxycorticosterone acetate (DOCA)-salt-induced hypertension. We evaluated the pathological role of ET(B) receptors in DOCA-salt-induced hypertension, cardiovascular hypertrophy, and renal damage by using the spotting-lethal (sl) rat, which carries a naturally occurring deletion in the ET(B) receptor gene.. Homozygous (sl/sl) rats exhibit abnormal development of neural crest-derived epidermal melanocytes and the enteric nervous system, and they do not live beyond 1 month because of intestinal aganglionosis and intestinal obstruction. The dopamine ss-hydroxylase (DssH) promoter was used to direct ET(B) transgene expression in sl/sl rats to support normal enteric nervous system development. DssH-ET(B) sl/sl rats live into adulthood and are healthy, expressing ET(B) receptors in adrenal glands and other adrenergic neurons. When homozygous (sl/sl) and wild-type (+/+) rats, all of which were transgenic, were treated with DOCA-salt, homozygous rats exhibited earlier and higher increases in systolic blood pressure than did wild-type rats. Chronic treatment with ABT-627, an ET(A) receptor antagonist, completely suppressed DOCA-salt-induced hypertension in both groups. Renal dysfunction and histological damage were more severe in homozygous than in wild-type rats. Marked vascular hypertrophy was observed in homozygous rats than in wild-type rats. Renal and vascular injuries were significantly improved by ABT-627. In DOCA-salt-treated homozygous rats, there were notable increases in renal, urinary, and aortic ET-1, all of which were normalized by ABT-627.. ET(B)-mediated actions are protective in the pathogenesis of DOCA-salt-induced hypertension. Enhanced ET-1 production and ET(A)-mediated actions are responsible for the increased susceptibility to DOCA-salt hypertension and tissue injuries in ET(B) receptor-deficient rats.

Topics: Acetylglucosaminidase; Animals; Animals, Genetically Modified; Aorta; Blood Pressure; Blood Urea Nitrogen; Body Weight; Desoxycorticosterone; Endothelin-1; Heart; Hypertension; Kidney; Organ Size; Rats; Rats, Mutant Strains; Receptor, Endothelin B; Receptors, Endothelin; Systole; Time Factors

Several recent studies have provided evidence that many of the hemodynamic and mitogenic actions of angiotensin II (Ang II) are mediated by endothelin-1 (ET-1). We hypothesized that Ang II and ET-1 act synergistically to promote a decline in renal function and the development of renal fibrosis in the deoxycorticosterone acetate (DOCA)-salt model of malignant hypertension and renal dysfunction. Experiments were conducted to determine the effects of ET(A) receptor antagonism (A-127722) and AT(1) receptor antagonism (candesartan cilexetil) on the development of renal fibrosis and the decline of renal function. Surgery was conducted on male, Sprague-Dawley rats to remove the right kidney and implant subcutaneously a time-release pellet containing DOCA. DOCA-treated rats were also given 0.9% NaCl to drink. After recovery from surgery, rats received one of four treatments via the drinking solution: (1) candesartan cilexetil (10 mg/kg/day), (2) A-127722 (10 mg/kg/day), (3) candesartan cilexetil plus A-127722, or (4) untreated controls. Over the course of a 3-week treatment period, systolic arterial pressure in all groups were elevated. However, this increase was significantly attenuated in the group given combined A-127722 and candesartan, but not with candesartan alone. Creatinine clearance, used as a measure of GFR, was significantly higher in rats treated with either or both drugs. At the end of the study, renal medullary tissue was harvested for determination of TGF-beta and fibronectin content (ELISA). TGF-beta levels were not reduced by either ET(A), AT(1), or combined ET(A) and AT(1) receptor blockade. Likewise, fibronectin content was similar among groups. These studies indicate that combined ET(A) and AT(1) receptor blockade may produce some improvement on hemodynamics, but have no effect on progression of renal damage in this non-renin-dependent model of hypertension.

Topics: Angiotensin II; Angiotensin Receptor Antagonists; Animals; Atrasentan; Benzimidazoles; Biphenyl Compounds; Blood Pressure; Body Weight; Desoxycorticosterone; Disease Models, Animal; Drug Therapy, Combination; Endothelin Receptor Antagonists; Endothelin-1; Hypertension; Kidney; Male; Natriuresis; Pyrrolidines; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Tetrazoles

Inhibition of cytochrome P-450 (CYP450) enzymes with cobalt chloride (CoCl2) prevented hypertension, organ hypertrophy, and renal injury induced by DOCA and salt (1% NaCl) in uninephrectomized (UNx) rats. Systolic blood pressure (SBP) rose to 193 +/- 6 mmHg by day 21 from control levels of 150 +/- 7 mmHg in response to DOCA-salt treatment, a rise that was prevented by CoCl2 (24 mg. kg-1. 24 h-1). The effects of DOCA-salt treatment, which increased protein excretion to 88.3 +/- 6.9 mg/24 h on day 21 from 9.0 +/- 1.1 mg/24 h on day 3, were prevented by CoCl2. CoCl2 also attenuated the renal and left ventricular hypertrophy and the increase in media-to-lumen ratio in hypertensive rats. DOCA-salt treatment increased excretion of endothelin (ET)-1 from 81 +/- 17 to 277 +/- 104 pg. 100 g body wt-1. 24 h-1 associated with a fourfold increase in 20-hydroxyeicosatetraenoic acid (20-HETE) excretion from 3.0 +/- 1.1 to 12.2 +/- 1.9 ng. 100 g body wt-1. 24 h-1 (days 3 vs. 21). CoCl2 blunted these increases by 58 and 72%, respectively. In aortic rings pulsed with [3H]thymidine, ET-1 increased its incorporation. Dibromododec-11-enoic acid, an inhibitor of 20-HETE synthesis, attenuated ET-1-induced increases in [3H]thymidine incorporation. We distinguished effects of CoCl2 acting via CO generation vs. suppression of CYP450-arachidonic acid metabolism by treating UNx-salt-DOCA rats with 1-aminobenzotriazole (ABT), which suppresses CYP450 enzyme activity, and compared these results to those produced by CoCl2. ABT reduced hypertension, as did CoCl2. Unlike CoCl2, ABT did not prevent organ hypertrophy and proteinuria, suggesting that these effects were partially related to CO formation. Blockade of the ETA receptor with BMS-182874 reduced SBP, organ hypertrophy, and proteinuria, indicating the importance of ET-initiated abnormalities to the progression of lesions in UNx-salt-DOCA.

Topics: Animals; Arachidonic Acid; Blood Pressure; Body Weight; Cytochrome P-450 Enzyme System; Desoxycorticosterone; Endothelin-1; Hydroxyeicosatetraenoic Acids; Hypertension; Kidney; Male; Myocardium; Organ Size; Proteinuria; Rats; Rats, Sprague-Dawley; Sodium Chloride

Previous studies showed a renoprotective effect of l-arginine in experimental uremia. Whether this was caused by an increased nitric oxide (NO) release or depended on l-arginine per se is not clear. Here, we evaluated whether chronic administration of an NO donor, molsidomine, controlled systemic blood pressure and renal disease progression and prolonged survival in rats with renal mass reduction (RMR). Rats with RMR received the following daily in the drinking water: group 1 (n = 21), no specific therapy (vehicle); group 2 (n = 12), molsidomine, 120 mg/L; group 3 (n = 9), lisinopril, 25 mg/L; and group 4 (n = 12), reserpine, 5 mg/L, hydralazine, 80 mg/L, and hydrochlorothiazide, 25 mg/L, from day 21 after surgery, when rats had hypertension and proteinuria, until the death of the vehicle-treated rats. Molsidomine normalized systemic hypertension, only partially reduced proteinuria and serum creatinine levels, but significantly prolonged animal survival, particularly in the early stage of the disease. Lisinopril at a similar systemic blood pressure was even better than molsidomine in limiting proteinuria, preserving renal function, and prolonging survival, but triple therapy, despite being effective on blood pressure, offered no renoprotection or prolonged survival. Endothelin-1 (ET-1) levels, formed in excessive amounts by the kidneys of these animals, were reduced by molsidomine and lisinopril, but not by triple therapy. The prolongation of survival by NO donor could be attributed to its effect of reducing ET levels, which in turn may limit the smooth muscle cell proliferation and matrix accumulation responsible for organ and, especially, myocardial fibrosis in uremia.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Pressure; Body Weight; Creatinine; Disease Progression; Eating; Endothelin-1; Hydralazine; Hydrochlorothiazide; Kidney; Lisinopril; Male; Molsidomine; Nephrectomy; Nitric Oxide; Nitric Oxide Donors; Nitrous Oxide; Rats; Rats, Sprague-Dawley; Reserpine

The renin-angiotensin system plays an important role in the pathophysiology of hypertension. We studied vascular function in the aorta of mouse Ren-2 transgenic rats (TGR(mRen2)27). Changes in isometric tension of isolated aorta of TGR(mRen2)27 and Sprague-Dawley rats (SD) were recorded in organ chambers. Contractions to angiotensin II (AII), big-endothelin and endothelin-1 (ET-1), but not KCl were decreased in TGR. Blockade of nitric oxide (NO)-synthase by L-NAME or removal of the endothelium did not alter these decreased contractions to ET-1 and AII in TGR, suggesting that receptors or signaling pathways of these two agonists are downregulated during hypertension. Contractions to norepinephrine (NE) were also lower in TGR, however blockade of NO-synthase by L-NAME or removal of the endothelium evoked similar contractions to NE in both strains, suggesting that basal release of NO reduces contractions to NE to a greater extent in transgenic than control rats. In the presence of L-NAME, acetylcholine evoked endothelium-dependent contractions (EDCF) in TGR, which were blocked by the thromboxane/prostaglandin H2 receptor antagonists SQ 30741, and partially by the thromboxane synthase inhibitor CGS 13080, suggesting that prostaglandin H2 is the mediator. Endothelium-dependent relaxation to acetylcholine was decreased in TGR, while endothelium-independent relaxations to sodium nitroprusside were similar in both strains. SQ 30741 did not improve relaxations to acetylcholine in TGR indicating that impaired relaxations to acetylcholine are due to a decreased acetylcholine-receptor mediated release of NO rather than increased release of EDCF. Thus, Ren-2 hypertension leads to marked alterations of vascular functions in the aorta. These changes could contribute to hypertension and its vascular complications in TGR(mRen2)27 rats.

Topics: Acetylcholine; Angiotensin II; Animals; Animals, Genetically Modified; Aorta; Blood Pressure; Body Weight; Endothelin-1; Endothelins; Endothelium, Vascular; Hypertension; Male; Mice; Muscle Contraction; Muscle Relaxation; Muscle, Smooth, Vascular; NG-Nitroarginine Methyl Ester; Norepinephrine; Protein Precursors; Rats; Rats, Sprague-Dawley; Renin

This is a study of the electron-immunocytochemical localization of nitric oxide synthase (type III) and endothelin in renal and mesenteric artery endothelial cells of normal (active) and hibernating hamsters, as well as hamsters exposed to the cold but not hibernating, and hamsters aroused for 2h following hibernation. In the renal artery of hibernating hamsters and cold-exposed hamsters, a subpopulation of nitric oxide synthase-positive endothelial cells displayed immunoprecipitate predominantly in the vicinity of the Golgi complex indicating intracellular translocation from the cytoplasm to the Golgi complex. In hibernating animals, the percentages of both nitric oxide synthase-positive and endothelin-positive endothelial cells were notably lower than those observed either in active, cold-exposed or aroused animals. These changes may reflect a reduced endothelial contribution to the maintenance of vascular tone in these vessels during hibernation and an upregulation of expression of nitric oxide synthase and endothelin in the endothelium early on during arousal from hibernation.

Topics: Animals; Arousal; Body Temperature; Body Weight; Cold Temperature; Cricetinae; Endothelin-1; Endothelin-2; Endothelin-3; Endothelins; Endothelium, Vascular; Hibernation; Humans; Male; Mesenteric Arteries; Mesocricetus; Microscopy, Immunoelectron; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Renal Artery

We have previously shown that in the rat a diet high in cholesterol and deficient in vitamin E and selenium results in hypercholesterolaemia and increased lipid oxidation. We utilized this model to determine whether rats given this diet develop impaired endothelium-dependent relaxation mediated by nitric oxide (NO) in mesenteric and in renal vessels. In addition, we tested whether the impairment is due to (i) decreased endothelial NO synthase activity, (ii) increased NO inactivation and/or (iii) increased production of the endothelium-derived constricting factors thromboxane A2/prostaglandin H2 and endothelin-1. We also investigated whether endothelial dysfunction induced by dyslipidaemia increases the sensitivity for the development of hypertension in response to high dietary salt.. Male Dahl salt-sensitive (DSS) rats were divided into three groups and received a standard diet (control group), a high (4%) cholesterol diet (HChol), or a high cholesterol diet deficient in the anti-oxidants vitamin E and selenium (HChol-Def). The NaCl content of these diets was 0.5%. After 18 weeks we studied endothelium-dependent relaxation in response to acetylcholine (ACh) in aortas and in isolated perfused preparations of mesenteric arteries and kidneys. In some experiments, ifetroban, a thromboxane A2/prostaglandin H2 receptor antagonist, was added to the organ bath or the perfusion buffer. Vascular responses to endothelin-1 as well as to BQ-123, an endothelin A receptor blocker, were studied in the isolated perfused kidneys. In addition, two extra groups of rats were fed a diet high in sodium chloride (2%): one of the groups received the normal cholesterol diet whereas the other group received the diet high in cholesterol and deficient in vitamin E and selenium.. Compared to normocholesterolemic rats, responses to ACh were significantly impaired in aortas, mesenteric arteries and kidneys of HChol-Def rats (P < 0.01). Endothelial NO synthase activity (conversion of [14C]L-arginine to [14C]L-citrulline) was similar in aortas of control, HChol and HChol-Def rats; thus suggesting that impaired endothelium-dependent relaxation in the HChol-Def rats was not due to decreased cNOS catalytic activity. Ifetroban improved the impaired endothelium-dependent relaxation in mesenteric vessels, but not in aortas and kidneys. Endothelin-1 (ET-1: 10(-13)-10(-11) mol/l) elicited NO-mediated relaxations in kidneys of control rats but not in kidneys of HChol-Def; blockade of ET-1 with BQ-123, an ET(A) receptor blocker, did not improve NO-mediated relaxation of HChol-Def. Despite impaired endothelium-dependent relaxation in renal and mesenteric vessels, HChol-Def DSS rats failed to develop hypertension (systolic blood pressure 144 +/- 1 in control and 150 +/- 2 mmHg in HChol-Def) but manifested a significant increase in sensitivity to the pressor effects of a high (2% NaCl) dietary salt content during the initial 10 weeks of the study, although the final blood pressure at 18 weeks was similar in both groups.. These studies support the notion that (i) products of lipid oxidation may reduce NO bioactivity without affecting endothelial NO synthase mass or catalytic activity, (ii) the mechanisms involved in the endothelial dysfunction induced by hypercholesterolaemia and oxidized lipids may differ among vascular beds, and (iii) decreased NO bioavailability does not necessarily result in systemic hypertension, but it may enhance the sensitivity to the hypertensinogenic effect of dietary salt.

Topics: Acetylcholine; Animals; Aorta; Blood Pressure; Body Weight; Diet; Disease Models, Animal; Endothelin-1; Endothelins; Endothelium, Vascular; Hypercholesterolemia; Hypertension; Kidney; Male; Mesenteric Arteries; Nitric Oxide; Nitric Oxide Synthase; Perfusion; Prostaglandin H2; Prostaglandins H; Rats; Thromboxane A2

The endothelial vasodilation mechanism(s) has been investigated in aortic rings of hypophysectomized male rats as well as hypophysectomized rats treated for 7 days with growth hormone (GH, 400 microg/kg, s.c.) or hexarelin (80 microg/kg, s.c.). Tissue preparations from intact animals were taken as controls. The results obtained indicate that the release of 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) from aortic rings of hypophysectomized rats was markedly reduced (51%; p<0.01) as compared with that of control preparations; the peak response to cumulative concentration of endothelin-1 (ET-1, from 10(-11) to 10(-5) M) was increased 2.4-fold (p<0.01) versus controls; the relaxant activity of acetylcholine (ACh, from 10(-10) to 10(-4) M) in norepinephrine-precontracted aortic rings was reduced by 39.5+/-4.4%. Pretreatment of hypophysectomized rats with GH or hexarelin markedly antagonized the hyperresponsiveness of the aortic tissue to ET-1 and allowed a consistent recovery of both the relaxant activity of ACh and the generation of 6-keto-PGF1alpha. Collectively these findings support the concept that dysfunction of vascular endothelial cells may be induced by a defective GH function. Because a replacement regimen of GH restored the somatotropic function and increased plasma insulin-like growth factor-I (IGF-I) concentrations in the hypophysectomized rats, it is suggested that IGF-I may have protected the vascular endothelium acting as a biologic mediator of GH action. In contrast to GH, hexarelin replacement neither increased body weight nor affected the plasma concentrations of IGF-I, indicating that its beneficial action on vascular endothelium was divorced from that on somatotropic function and was likely due to activation of specific endothelial receptors.

Topics: 6-Ketoprostaglandin F1 alpha; Acetylcholine; Animals; Aorta; Body Weight; Endothelin-1; Endothelium, Vascular; Enzyme Inhibitors; Homeostasis; Human Growth Hormone; Humans; Hypophysectomy; Male; Oligopeptides; omega-N-Methylarginine; Protective Agents; Rats; Rats, Sprague-Dawley; Vasodilation

Nephropathy is an important complication of diabetes mellitus (DM). The plasma endothelin 1 (ET-1) levels are increased in DM, and ET-1 may cause deleterious effects on renal function. We, therefore, investigated whether changes in ET receptors occur in the DM rabbit kidney.. Nine adult New Zealand White rabbits were injected with alloxan, of which 6 became diabetic; the other 3 acted as alloxan-treated controls. Six age-matched healthy rabbits served as controls. At 6 months, following cervical dislocation, the kidneys were removed, and sections (cortex and medulla) were incubated with ET(A) and ET(B) radioligands to produce low- and high-resolution autoradiographs. Immunohistochemical localization of ET-1 immunoreactivity was also performed.. There was greater ET(A) and ET(B) receptor binding in the control (ET(A) p = 0.0003; ET(B) p < 0.0001) and DM (ET(A) p = 0.001; ET(B) p < 0.0001) rabbits in the medulla as compared with the cortex. DM kidneys showed a significant increase in ET(A), but not ET(B), binding in the cortex (p < 0.0001) and in the medulla (p < 0.0001). High-resolution autoradiographs revealed striking [(125)I]-ET-1 receptor binding predominantly to the glomeruli. Immunohistochemistry revealed dense ET-1 immunoreactivity associated with the renal tubules, but the glomeruli exhibited no staining. Alloxan-treated controls had similar results to age-matched controls.. There are regional differences in both ET(A) and ET(B) binding in control and DM kidneys. ET(A) receptor binding sites are increased in the DM kidney (cortex and medulla). ET-1 may act in a paracrine fashion on the glomeruli. These changes may contribute to the pathogenesis of diabetic nephropathy.

Topics: Alloxan; Animals; Autoradiography; Azepines; Blood Glucose; Blood Urea Nitrogen; Body Weight; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Disease Models, Animal; Endothelin-1; Endothelins; Immunoenzyme Techniques; Iodine Radioisotopes; Kidney; Male; Oligopeptides; Peptide Fragments; Potassium; Rabbits; Radioligand Assay; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Sodium; Up-Regulation

The present experiments were designed to investigate the effect of ATZ1993 [3-carboxy-4,5-dihydro-1-[1-(3-ethoxyphenyl)propyl]-7-(5-pyrimidinyl)met hoxy-[1H]-benz[g]indazole] on the intimal hyperplasia after balloon endothelial denudation of the rabbit carotid artery. ATZ1993 inhibited the specific [125I]endothelin (ET)-1 binding not only to ET-receptor subtype A (ET(A)) with a pKi value of 8.69+/-0.02, but also to ET-receptor subtype B (ET(B)) with a pKi value of 7.20+/-0.03. Counterscreening in the binding assay (30 different receptors) confirmed that ATZ1993 had a high selectivity for ET receptors. Increases in intima:media ratio and DNA content in the vessel wall were significantly (P < 0.005) inhibited by ATZ1993 in a daily dose of 30 mg x 200 ml(-1) x kg(-1) for 1 week before and 6 weeks after balloon denudation. Inhibition of the intimal hyperplasia with ATZ1993 was determined as approximately 77% for increases in intima:media ratio and DNA content. Plasma concentrations of ATZ1993 ranged between 121.6+/-26.6 and 131.7+/-20.9 nM throughout experimental periods. Mean arterial blood pressure, heart rate and body weight gain remained unaffected by administering ATZ1993. These results demonstrate that ATZ1993 is a novel nonpeptide and nonselective ET(A)/ET(B)-receptor antagonist, and the agent when administered orally inhibits effectively intimal hyperplasia after balloon denudation of the rabbit carotid artery.

Topics: Administration, Oral; Angioplasty, Balloon; Animals; Blood Pressure; Body Weight; Carotid Artery Injuries; Carotid Artery, Common; Endothelin Receptor Antagonists; Endothelin-1; Heart Rate; Humans; Hyperplasia; Indazoles; Male; Muscle, Smooth, Vascular; Rabbits; Receptors, Endothelin; Swine; Tunica Intima

The present study was designed to assess whether the orally active and highly specific endothelin A (ET(A)) receptor antagonist LU 135252 affects progressive renal dysfunction in a hypertensive rat model of renal damage, ie, the uninephrectomized (UNX) stroke-prone spontaneously hypertensive rat (SHRsp). The animals were examined on a normal salt (0.25%) diet and, to sensitize the kidney to hypertensive injury, also on a high salt (3%) diet. Stereological methods were used to quantify indices of glomerulosclerosis, vascular damage, and tubulointerstitial damage. Treatment with LU 135252 (100 mg/kg body wt) did not affect systolic blood pressure (BP) in animals on a normal salt diet during the whole period of the experiment (18 weeks) or in salt-loaded animals until week 10; subsequently, BP was slightly but significantly lower in salt-loaded UNX-SHRsp given LU 135252. Between weeks 6 and 12, 40% of the untreated UNX-SHRsp on a high salt diet, but none on a standard salt diet, died; such mortality was completely prevented by LU 135252. Indices of renal damage were more abnormal in salt-loaded UNX-SHRsp compared with UNX-SHRsp on a normal salt diet. Development of glomerulosclerosis and tubulointerstitial and vascular damage in UNX-SHRsp on high salt was completely prevented by LU 135252. The respective indices were no longer significantly different from those of salt-loaded sham-operated SHRsp controls. In the less severely damaged kidneys of UNX-SHRsp on normal salt, treatment with LU 135252 tended to ameliorate the indices, but the difference was not statistically significant. The results document a role of the ET system, specifically of ET(A) receptors, in the development of progressive renal injury in salt-loaded UNX-SHRsp. LU 135252 completely prevented death and renal damage resulting from salt loading.

Topics: Animals; Blood Pressure; Body Weight; Cerebrovascular Disorders; Endothelin Receptor Antagonists; Endothelin-1; Kidney; Male; Nephrectomy; Phenylpropionates; Pyrimidines; Rats; Rats, Inbred SHR; Receptor, Endothelin A; Sodium, Dietary

The effects of vasodepressor (acetylcholine and bradykinin) and pressor [electrical stimulation of the spinal sympathetic outflow, norepinephrine and endothelin-1 (ET-1)] stimuli were determined in rats with 2- and 5-week untreated streptozotocin-induced diabetes (blood glucose 400 and >500 mg/dl, respectively). In pentobarbital-anesthetized animals, the hypotensive response to an intravenous dose of acetylcholine or bradykinin was unaffected in animals treated for 2 weeks with streptozotocin but was significantly reduced (22% and 48%, respectively) after 5 weeks. However, the pressor responses to ET-1 were significantly decreased in animals that had been given streptozotocin 2 (38%) and 5 (45%) weeks previously. In contrast, the vasoconstrictor effects of electrical stimulation of the spinal cord outflow and norepinephrine were significantly inhibited (47% and 30%, respectively) at 5 weeks, but not at 2 weeks, after streptozotocin administration. These results indicate that, in untreated streptozotocin diabetes, a substantial impairment of vascular reactivity to ET-1 appears more rapidly than inhibition of the pressor responses to endogenous and exogenous norepinephrine or to vasodilator substances that require integrity of vascular endothelial cell function to produce their normal effects.

Topics: Acetylcholine; Animals; Blood Glucose; Body Weight; Bradykinin; Diabetes Mellitus, Experimental; Electric Stimulation; Endothelin-1; Male; Norepinephrine; Rats; Rats, Sprague-Dawley; Spinal Cord; Vasoconstrictor Agents

Angiotensin II (Ang II) stimulates endothelin-1 (ET-1) production in glomerular endothelial and mesangial cells and in cardiac fibroblasts in vitro. We investigated the effects of Ang II in vivo (200 ng/kg/min for 2 weeks) with or without the ETA receptor antagonist LU135252 (50 mg/kg/day) on blood pressure, renal and myocardial ET-1 protein expression, and [125I]ET-1 uptake in male Wistar-Kyoto (WKY) rats. ET-1 was extracted from whole kidneys and ventricular myocardium and was measured by radioimmunoassay (pg ET-1/g tissue). Organ tissue uptake was calculated as percentage of total DPM recovered after i.v. administration of radiolabeled [125I]ET-1. Ang II treatment increased blood pressure by 35 +/- 3 mm Hg, which was partly reduced by LU135252 (15 +/- 2 mm Hg, p < 0.05). LU135252 in part prevented the impaired weight gain induced by Ang II (p < 0.05). Ang II induced a threefold increase in expression of ET-1 (pg/g tissue) in kidneys (from 19 +/- 2 to 58 +/- 10, p < 0.05), which was normalized by LU135252 (20 +/- 9, p < 0.05). In myocardial tissue, Ang II had only minor effects (5 +/- 1 vs. 3.6 +/- 1, n.s.). However, concomitant LU135252 treatment reduced myocardial ET-1 levels (1.4 +/- 0.4, p < 0.05 vs. Ang II and control). Ang II increased uptake of [125I]ET-1 in kidneys (from 6.9 +/- 0.1% to 10.9 +/- 0.9% of total DPM, p < 0.05) but not in myocardium (1.45 +/- 0.26% vs. 1.59 +/- 0.18% of total DPM), which was unaffected by LU135252 treatment. These data suggest that the kidney, but not the ventricular myocardium, is a target for Ang II-mediated activation of the ET system in vivo, leading to expression and uptake of ET-1. ETA antagonists may provide a new approach to inhibit production and effects of ET-1 in diseases associated with increased activity of the renin-angiotensin system.

Topics: Angiotensin II; Animals; Blood Pressure; Body Weight; Endothelin Receptor Antagonists; Endothelin-1; Heart; Kidney; Male; Myocardium; Phenylpropionates; Pyrimidines; Rats; Rats, Inbred WKY; Receptor, Endothelin A

We studied target organ-protective effects of aracepril, an angiotensin-converting enzyme inhibitor, and the expression of endothelin-1 (ET-1) and nitric oxide synthase (NOS) mRNA. Aracepril (30 mg/kg) was administered orally to Izumo strain of stroke-prone spontaneously hypertensive rats (SHR-SP/Izm) for 8 weeks from 4 weeks of age and for 4 weeks from 8 weeks of age. The expression of ET-1 and endothelial NOS (eNOS) mRNA in the heart, aorta, kidneys, and brain cortex, and the expression of neuronal NOS (bNOS) mRNA in brain cortex, were analyzed by RT-PCR/Southern blotting or RNase protection analysis. Administration of aracepril markedly lowered blood pressure and decreased left ventricular weight in SHR-SP/Izm. Expression of ET-1 mRNA in the heart, kidneys, and brain was significantly enhanced in SHR/SP/Izm compared with that in WKY/Izm. Aracepril significantly decreased the expression of ET-1 mRNA, whereas there was no significant change of that in the aorta. Although expression of eNOS mRNA in the heart, aorta, and kidneys did not show any significant difference between the two strains of rats, administration of aracepril for 8 weeks significantly decreased the expression of eNOS and bNOS mRNA in brain tissue. These results suggested that aracepril may protect major target organs by modifying the expression of ET-1 and NOS mRNA, in addition to its hypotensive effect.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Body Weight; Cardiovascular System; Endothelin-1; Hemodynamics; Male; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Organ Size; Rats; Rats, Inbred SHR; RNA, Messenger; Tissue Distribution

To characterize the effects of endothelin-1 and of Bosentan, a mixed endothelin antagonist, on hepatic hemodynamics in cirrhotic animals in vivo and on hepatic microvascular exchange in the perfused rat liver.. Biliary cirrhosis was induced by bile duct ligation, and micronodular cirrhosis by chronic exposure to phenobarbital/CCl4 in male rats. Hepatic hemodynamics were studied under basal conditions and after administration of Bosentan (3-30 mg/kg) by the microsphere technique. Microvascular exchange was assessed in the in situ perfused rat liver by the multiple indicator dilution technique.. Bosentan lowered portal pressure in a dose-dependent fashion; at the highest dose tested, this decrease averaged -29+/-11 and -26+/-8% in biliary and micronodular cirrhosis, respectively (p<0.01). This was achieved mainly via a marked decrease in hepatic arterial flow. In the perfused liver, endothelin-1 induced a dose-dependent vasoconstriction; up to 10(-9) mol/l; this was not associated with any effect on viability. At this dose, endothelin-1 markedly decreased extravascular albumin space in both controls and micronodular cirrhosis; this could be antagonized by Bosentan 10(-5) mol/l.. Endothelin-1 affects hepatic microvascular exchange, presumably by a direct effect on hepatic sinusoidal endothelial cells. A mixed endothelin antagonist lowers portal pressure in vivo, presumably by acting on hepatic stellate cells, and counteracts the microvascular effects of endothelin-1 in vitro. These properties could prove useful in treatment of portal hypertension.

Topics: Animals; Bile Acids and Salts; Bile Ducts; Bilirubin; Blood Pressure; Body Weight; Bosentan; Carbon Tetrachloride Poisoning; Cardiac Output; Endothelin-1; Hemodynamics; Hepatic Artery; Liver; Liver Circulation; Liver Cirrhosis, Biliary; Male; Metabolic Clearance Rate; Microcirculation; Organ Size; Phenobarbital; Portal System; Rats; Rats, Sprague-Dawley; Sulfonamides

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide, which also potentiates contractions to norepinephrine in human internal mammary and coronary vessels. Exercise causes a redistribution of blood flow, i.e., the increase in working muscles that is partly attributable to a decrease in visceral blood flow. We hypothesized that exercise causes a tissue-specific increase in ET-1 expression in internal organs. We studied whether exercise affects expression of preproET-1 mRNA in the kidneys and lungs. The rats performed treadmill running (0% grade) for 45 min at a speed of 25 m/min. The plasma concentrations of ET-1, epinephrine, and norepinephrine were greater in the exercise rats than in the sedentary control rats. The expression of preproET-1 mRNA in the kidneys was markedly higher in the exercise rats than in the sedentary control rats, whereas that in the lungs did not differ between the two groups. Therefore, the present study provides a possibility that the exercise-induced increase in production of ET-1 in the kidneys causes vasoconstriction and hence decreases blood flow in the kidneys through its direct vasoconstrictive action and/or its indirect effect of enhancing vasoconstrictions to norepinephrine.

Topics: Animals; Body Weight; Endothelin-1; Endothelins; Epinephrine; Hemodynamics; Immunoenzyme Techniques; Kidney; Lung; Male; Norepinephrine; Organ Size; Physical Exertion; Polymerase Chain Reaction; Protein Precursors; Rats; Rats, Wistar; RNA, Messenger

1. The present study assessed local regulation of vascular tone of euthermic (control), cold control and hibernating golden hamsters. Sympathetic neurotransmission in the renal artery, the long term effects of hibernation on perivascular nerve activity, and the responsiveness of femoral artery to a number of neurotransmitters and hormones with both constrictor and dilator actions during hibernation are described. 2. The contractile responses of the renal arterial rings to transmural nerve stimulation (80 V, 0.1 ms, 4-64 Hz, for 1 s) were negligible in controls, significantly increased at higher frequencies of stimulation in cold controls and markedly enhanced in the hibernating group at all frequencies tested. The contractile responses to exogenous noradrenaline (NA; 0.1-100 microM) were significantly increased in the renal arteries of hibernating hamsters compared with controls, but not compared with cold controls. Responses to exogenous ATP (1-3000 microM) and KCl (120 mM) were similar among all experimental groups. 3. The maximal contractile responses of femoral arterial rings to the sympathetic co-transmitter ATP and 5-hydroxytryptamine were increased by approximately 124% and 99%, respectively, in hibernating compared with cold control preparations without a change in the concentration of agonist that produces half-maximal response. However, the responses to NA were not altered during hibernation. 4. Vasoconstriction of femoral arterial rings in response to arginine vasopressin was significantly enhanced in both cold controls and hibernating groups, while vasoconstriction in response to endothelin-1 and KCl was unaltered. 5. The dilator responses of femoral arterial rings to acetylcholine, sodium nitroprusside and adenosine were not different among the groups. 6. It is suggested that the marked augmentation of sympathetic neurotransmission, selective supersensitivity of the vascular smooth muscle to sympathetic contractile agents and unaltered vasodilatory mechanisms may provide a means for maintenance of vascular tone and peripheral resistance during hibernation.

Topics: Adenosine Triphosphate; Animals; Body Weight; Cricetinae; Electric Stimulation; Endothelin-1; Femoral Artery; Hibernation; Mesocricetus; Muscle Contraction; Muscle Tonus; Muscle, Smooth, Vascular; Potassium Chloride; Renal Artery; Serotonin; Sympathetic Nervous System; Synaptic Transmission; Vasoconstriction; Vasodilation

We have evaluated the effects of a new calcium channel blocker, manidipine, given at both high, hypotensive and low, non-hypotensive doses, on vascular morphology, response to endothelin-1 and ICAM-1 production in mesenteric small resistance arteries of spontaneously hypertensive rats (SHR).. Ten SHR were treated with manidipine 3 mg/kg per day (high dose) and 10 with manidipine 0.3 mg/kg/per day (low dose). The drug was administered by gavage from the 4th to 12th weeks of age. Eighteen Wistar-Kyoto (WKY) rats and 18 SHR were kept untreated as controls. Rats were killed at 13 weeks. Mesenteric small arteries were dissected and mounted on a micromyograph for determination of indexes of vascular structure (media thickness, wall thickness, media/lumen ratio).. Systolic blood pressure was significantly reduced by the high dose of the drug, while no effect was observed with low-dose manidipine. A reduction in the media/lumen ratio was observed only in SHR treated with high-dose manidipine. The response to endothelin-1 in untreated SHR was significantly lower in comparison with WKY; a significant reduction was observed in SHR treated with high-dose manidipine. ICAM-1 vascular concentrations were higher in untreated SHR than in WKY controls. Both high- and low-dose manidipine reduced ICAM-1 concentrations toward normalization.. Manidipine at high, hypotensive, but not at low, non-hypotensive doses has been proven to reduce structural alterations in mesenteric small resistance arteries, and to normalize vascular responses to endothelin-1. In addition, manidipine, at both low and high doses, may reduce ICAM-1 vascular production, thus suggesting a possible anti-atherogenic effect.

Topics: Animals; Antihypertensive Agents; Arteries; Blood Pressure; Body Weight; Calcium Channel Blockers; Dihydropyridines; Endothelin-1; Intercellular Adhesion Molecule-1; Male; Muscle, Smooth, Vascular; Nitrobenzenes; Piperazines; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Vascular Resistance

We compared the effects of endothelin-1 (ET-1) on intracellular pH, intracellular [Ca2+]i, and cell contraction in hypertrophied adult ventricular myocytes from ascending aortic banded rats and age-matched controls. Intracellular pH (pH(i)) was measured in individual myocytes with SNARF-1, and [Ca2+]i was measured with indo-1, simultaneous with cell motion. Experiments were performed at 36 degrees C in myocytes paced at 0.5 Hz in Hepes-buffered solution (pH(o) 7.40) containing 1.2 mM CaCl2. At baseline, calibrated pH(i), diastolic and systolic [Ca2+]i values, and the amplitude of cell contraction were similar in hypertrophied and control myocytes. Exposure of the control myocytes to 10 nM ET-1 caused an increase in the amplitude of cell contraction to 163+/-22% of baseline (P < 0.05), associated with intracellular alkalinization (pH(i) + 0.08+/-0.02 U, P < 0.05) and a slight increase in peak systolic [Ca2+]i (104+/-11% of baseline, P < 0.05). In contrast, in the hypertrophied myocytes, exposure to ET-1 did not increase the amplitude of cell contraction or cause intracellular alkalinization (-0.01+/-0.02 U, NS). Similar effects were observed in the hypertrophied and control myocytes in response to exposure to 10 nM angiotensin II. ET-1 also increased the rate of recovery from intracellular acidosis induced by the washout of NH4Cl in the control cells, but did not do so in the hypertrophied cells. In the presence of 10 microM 5-(N-ethyl-N-isopropyl)-amiloride, which inhibits Na+-H+ exchange, ET-1 did not cause a positive inotropic effect or intracellular alkalinization in control cells. The activation of protein kinase C by exposure to phorbol ester caused intracellular alkalinization and it increased the rate of recovery from intracellular acidification induced by an NH4Cl pulse in control cells but not in hypertrophied cells. ET-1, as well as angiotensin II, and phorbol ester, fail to stimulate forward Na+-H+ exchange in adult hypertrophied myocytes. These data suggest a defect in the coupling of protein kinase C signaling with Na+-H+ exchange in adult hypertrophied myocytes.

Topics: Amiloride; Ammonium Chloride; Angiotensin II; Animals; Body Weight; Calcium; Cardiomegaly; Cell Size; Cells, Cultured; Endothelin-1; Hydrogen-Ion Concentration; Male; Myocardium; Phorbol Esters; Protein Kinase C; Rats; Rats, Wistar; Sodium-Hydrogen Exchangers

We investigated vascular function in mouse Ren-2 transgenic rats with hypertension. Mesenteric resistance arteries of transgenic and Sprague-Dawley rats (controls) were isolated at ages 6 and 12 wk and suspended in myographs for isometric tension recording. Systolic blood pressure was higher in transgenic than control rats (P < 0.05). Contractions to norepinephrine and endothelin-1 were comparable in transgenic and control rats, but the sensitivity decreased with age in both strains (P < 0.05). Contractions to angiotensin I were comparable in 6-wk-old transgenic rats and controls, but the response to angiotensin I was more pronounced in transgenic rats at 12 wk of age. Contractions to angiotensin II were higher in transgenic rats and decreased with age in both strains. Preincubation with the cyclooxygenase inhibitor meclofenamate or the thromboxane receptor antagonist SQ-30741 blunted the response only in 6-wk-old transgenic rats. In quiescent vascular rings, acetylcholine evoked endothelium-dependent contractions after inhibition of nitric oxide formation by N omega-nitro-L-arginine methyl ester only in transgenic rats. These contractions were inhibited by SQ-30741 (P < 0.05) but not by the thromboxane synthase inhibitor CGS-13080. Contractions to the thromboxane analogue U-46619 were comparable in both strains at the age of 6 wk; sensitivity was increased in transgenic rats at 12 wk (P < 0.05). In conclusion, in mesenteric resistance arteries of Ren-2 transgenic rats I) contractions to angiotensin I and II but not to norepinephrine and endothelin-1 are increased, and 2) acetylcholine as well as angiotensin II modulate endothelium-dependent contractions mediated by prostaglandin H2. These alterations together with increased sensitivity to thromboxane could contribute to maintenance as well as to impaired tissue perfusion of this form of hypertension.

Topics: Acetylcholine; Angiotensin II; Animals; Animals, Genetically Modified; Blood Pressure; Body Weight; Endothelin-1; Endothelium, Vascular; Hypertension; Male; Mesenteric Arteries; Mice; Norepinephrine; Potassium Chloride; Prostaglandins; Rats; Rats, Sprague-Dawley; Renin; Vasoconstriction; Vasoconstrictor Agents

We investigated protein kinase C participation in the contractile response to 5-hydroxytryptamine (5-HT), and in the interaction between 5-HT and endothelin-1, in aortas from control and diabetic rats. Diabetic rats display attenuated reactivity to 5-HT (i.e., approximately 47% of control maximum). The protein kinase C inhibitor calphostin C (1 microM) significantly reduced responses to 5-HT only in aortas from control rats. In diabetic rats, maximum responses to 5-HT, in the presence of endothelin-1 (3 nM), were not significantly different to controls. The additional presence of calphostin C significantly reduced responses only in aortas from diabetic rats. These results may indicate an abnormality in the protein kinase C second messenger system during diabetes.

Topics: Animals; Aorta, Thoracic; Blood Glucose; Body Weight; Diabetes Mellitus, Experimental; Endothelin-1; Enzyme Activation; Enzyme Inhibitors; In Vitro Techniques; Male; Muscle Contraction; Muscle, Smooth, Vascular; Naphthalenes; Protein Kinase C; Rats; Rats, Wistar; Serotonin

1. The present experiments were designed to investigate the effect of long-term oral nicotine (10 mg/200 ml/kg/day for 7 weeks) on the intimal hyperplasia after endothelial removal of the rabbit carotid artery. 2. The plasma concentrations of nicotine were determined to be 11.7-12.5 ng/ml during the term of administration and corresponded to the plasma levels in human smokers. 3. Six weeks after the endothelial removal, light microscopy revealed a marked intimal hyperplasia. Administration of nicotine tended to accelerate the intimal hyperplasia, which was estimated by comparing the histological findings, DNA content and wet weight of the vessel wall. 4. Acetylcholine- and A23187-induced endothelium-dependent relaxations were greatly impaired in the hyperplastic artery strips. The impairment of relaxations tended to be accelerated in the nicotine group. Sodium nitroprusside-induced relaxation was not different between the control and the hyperplastic artery strips and remained unaffected in the nicotine group. 5. The concentrations of endogenous nitric oxide (NO) synthesis inhibitors, NG-monomethyl-L-arginine (L-NMMA) and asymmetrical NG,NG-dimethyl-L-arginine (ADMA) were significantly more increased in the regenerated endothelial cells compared with those in the control endothelial cells. The concentrations of L-NMMA and ADMA in the regenerated endothelial cells were significantly increased by as much as 1.3 x 10(-6) and 5.6 x 10(-7) M, respectively, in the nicotine group. 6. Immunoreactive endothelin-1 was significantly increased in the hyperplastic vessel wall (2.4 times that of the control) in 6 weeks. Administration of nicotine tended to increase the level. 7. It seems possible to assume from these results that, although, under the present experimental conditions, nicotine exhibited a tendency to accelerate the intimal hyperplasia after endothelial removal, the longer exposure to nicotine or a higher dose of the agent or both would significantly accelerate the intimal hyperplasia through the enhanced impairment of endothelium-derived relaxing factor/ NO production, which might be brought about by the enhanced increases in L-NMMA and ADMA concentrations, and the enhanced increase in endothelin-1 in the vessel wall.

Topics: Animals; Arginine; Body Weight; Carotid Arteries; Endothelin-1; Endothelium, Vascular; Hyperplasia; Male; Muscle Relaxation; Muscle, Smooth, Vascular; Nicotine; Nitric Oxide Synthase; omega-N-Methylarginine; Rabbits; Tunica Intima

Chronic pressure overload is known to increase cardiac mass and expression levels of both atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) mRNAs. Although mechanical stretching of cardiac myocytes could cause these changes, humoral factor(s) secondary to pressure overload may also be involved. To dissociate humoral effects from the effects of mechanical loading on cardiac hypertrophic responses, we examined expression of ANP and BNP at both mRNA and protein levels and proportions of myosin isoforms in transplanted cervical hearts that were mechanically unloaded under conditions with or without hypertension by aortic coarctation. Seven days after transplantation, cardiac atrophy that usually occurs in transplanted hearts without hypertension by coarctation was prevented in the transplanted hearts with hypertension by coarctation. The levels of expression of ANP and BNP mRNAs were increased in the transplanted hearts with relative to those without hypertension by coarctation. The plasma level of angiotensin II was higher in rats with than without hypertension by coarctation. Plasma endothelin-1 levels were not significantly different between the two groups. In addition, levels of expression of ANP and BNP mRNAs were increased in the transplanted hearts without hypertension relative to those in the in situ hearts. The proportion of the V3 myosin isoform was also increased in the transplanted hearts without hypertension relative to the in situ hearts. These results indicate that humoral factor(s) secondary to the pressure overload produced by aortic coarctation enhanced the cardiac hypertrophic response and elevated the levels of mRNAs encoding these embryonic markers. Moreover, our findings regarding ANP and BNP expression in the transplanted hearts provide additional evidence that the fetal genes are reexpressed during the process of cardiac atrophy as well as in cardiac hypertrophy.

Topics: Angiotensin II; Animals; Aortic Coarctation; Atrial Natriuretic Factor; Atrophy; Blood Pressure; Body Weight; Cardiomegaly; Endothelin-1; Heart Rate; Heart Transplantation; Hypertension; Male; Myosins; Natriuretic Peptide, Brain; Nerve Tissue Proteins; Rats; Rats, Inbred Lew; RNA, Messenger; Transcription, Genetic; Transplantation, Heterotopic; Transplantation, Isogeneic

To determine the changes in serum angiotensin II (Ang II) and endothelin-1 levels induced by vanadium treatment of sugar-fed rats in order to investigate the relationship between changes in blood pressure and Ang II and endothelin-1 levels.. Male spontaneously hypertensive rats (SHR) were fed starch (control), sucrose, and sucrose plus vanadium compounds at various concentrations. The systolic blood pressure of the rats was estimated by tail-cuff plethysmography. Serum Ang II and endothelin-1 levels were measured by radioimmunoassay.. There were increases in systolic blood pressure (by 8%) and in serum Ang II (by 20%) in sucrose-fed SHR compared with control. In sucrose plus vanadium-fed SHR, the lowering of the systolic blood pressure (by 11-16% of the sucrose-fed value) was accompanied by a significant decrease in Ang II levels (by 25-60% of the sucrose-fed value) and an increase in endothelin-1 level (by 61-76% of the sucrose-fed value).. That Ang II levels are elevated in sucrose-induced hypertension and decreased after vanadium therapy suggests that the renin-angiotensin system plays a role in the induction of hypertension in this model. On the other hand, the elevation of endothelin-1 levels associated with a decreased systolic blood pressure might be secondary to vanadium stimulation of endothelial cells. The data suggest that endothelin-1 is not involved in sugar-induced elevations of the blood pressure.

Topics: Angiotensin II; Animals; Blood Pressure; Body Weight; Dietary Sucrose; Endothelin-1; Hypertension; Male; Radioimmunoassay; Rats; Rats, Inbred SHR; Vanadium

Diabetes Mellitus (DM) is a major risk factor for erectile dysfunction in both patients and animal models. The pathogenesis of this dysfunction has not been fully elucidated. However, alterations in the synthesis of a number of vasoactive compounds, such as nitric oxide (NO) and prostacyclin (PGI2), have been reported in various diabetic tissues. The interaction between NO, PGI2 and endothelin-1 (ET-1), a powerful vasoconstrictor and smooth muscle cell mitogen, is thought to be important in maintaining vascular tone and the erectile process. We investigated the density and distribution of ET-1 and endothelin receptor subtypes in cavernosal tissue and assessed any changes brought about by DM in a rabbit model.. DM was induced in New Zealand White rabbits using alloxan. Penises were excised from the diabetic rabbits three months (n = 6) and six months (n = 6) after the induction of DM. Low and high resolution autoradiography was performed using radioligands for ET-1, endothelin A (ETA) and endothelin B (ETB) receptors and were analyzed densitometrically. The results were compared with those from six age-matched healthy control rabbits for each group. Immunohistochemical localization of ET-1 immunoreactivity was also performed, together with ultrastructural evaluation of the corpus cavernosum.. ET-1, ETA and ETB receptor binding sites were primarily localized to the smooth muscle cells of the corpus cavernosum and the endothelium lining the cavernosal spaces. A significant increase in ETB receptor binding sites was found only in cavernosal tissue six months after induction of DM, when compared with age-matched healthy controls. These receptor changes were accompanied by ultrastructural changes in the corpus cavernosum indicative of an early, atherosclerosis-like process.. The autoradiographic and immunohistochemical findings in this study suggest that ET-1 may have a role in the pathophysiology of diabetic ED. This peptide may be released in an autocrine fashion causing cavernosal smooth muscle cell (CSMC) contraction and/or proliferation.

Topics: Animals; Autoradiography; Binding Sites; Blood Glucose; Body Weight; Cholesterol; Diabetes Mellitus, Experimental; Endothelin-1; Erectile Dysfunction; Immunohistochemistry; Male; Penis; Rabbits; Receptor, Endothelin B; Receptors, Endothelin

Pharmacological control of hypertension has contributed to a significant decrease in cardiovascular morbidity and mortality, although the beneficial effect on cardiac and renal diseases has been far more modest than the reduction in stroke. The endothelium plays a crucial homeostatic role in the regulation of vascular tone thrombogenesis and vascular remodeling. We studied the relationship between endothelial dysfunction and cardiorenal injury in hypertensive rats and evaluated the effects of two classes of antihypertensive agents commonly used in the clinical setting, a diuretic (DIU) and an ACE inhibitor (CEI).. Dahl salt-sensitive rats (DS) given high dietary salt (4% NaCl) developed hypertension (systolic blood pressure [SBP], 218+/-9 versus 147+/-3 mm Hg in DS given 0.5% NaCl; P<.001), which was associated with impaired endothelium-dependent relaxations (EDRs) in aortic rings (ED50, 5.44+/-.18 versus 7.51+/-.10; P<.05) and mesenteric vessels (area under the curve, 299+/-11 versus 217+/-11 arbitrary units; P<.05). Hypertensive DS also demonstrated depressed nitric oxide synthase activity in the aorta (0.76+/-.15 versus 2.83+/-.17 nmol x min(-1) x g protein(-1); P<.05), left ventricular hypertrophy (0.43+/-.02 versus 0.29+/-.02 g ventricular weight/100 g body weight; P<.05), glomerular injury (histological injury score: 151+/-8 versus 11+/-2; P<.05), and increased urinary protein excretion (95+/-21 versus 25+/-5 mg/24 hours; P<.05). Treatment of DS rats with the CEI perindopril (4.56 mg x kg(-1) x d(-1)) did not affect SBP (225+/-6 mm Hg) but modestly improved EDR (ED50: 6.07+/-.37; P<.05 versus hypertensive DS) as well as proteinuria and glomerular histology. Addition of the DIU indapamide (1.44 mg x kg(-1) x d(-1)) normalized SBP (151+/-2 mm Hg; P<.05), EDR (ED50, 7.33+/-.08; P<.05), left ventricular hypertrophy (0.27+/-.01 g/100 g body weight; P<.05), and proteinuria (31+/-4 mg/24 hours; P<.05) and prevented glomerular injury (injury score: 30+/-2; P<.05). Monotherapy with DIU reduced SBP (175+/-3 mm Hg; P<.05) and normalized EDR and left ventricular hypertrophy but did not provide effective renal protection. In hypertensive DS, impaired EDR and left ventricular hypertrophy were positively correlated with SBP. In addition, we found a significant correlation between cardiac hypertrophy and endothelial dysfunction. Indeed, a hierarchical regression analysis revealed that impaired aortic EDR, and therefore decreased aortic compliance, positively contributed to left ventricular hypertrophy in addition to but independently of SBP [F(2,37)=6.29; P=.004].. These studies suggest a dissociation of the endothelial, cardiac, and renal effects of antihypertensive therapy in hypertension and may explain the variable success of antihypertensive regimens in treating hypertension while preventing cardiac and renal damage.

Topics: Acetylcholine; Animals; Aorta; Blood Pressure; Body Weight; Endothelin-1; Endothelium, Vascular; Heart; Hypertension; In Vitro Techniques; Kidney; Male; Muscle Relaxation; Muscle, Smooth, Vascular; Myocardium; Nitric Oxide Synthase; Organ Size; Rats; Rats, Inbred Strains; Sodium, Dietary; Systole; Vasodilation

Plasma endothelin (ET-1) and renal endothelin are two distinct functional systems involved in maintaining blood volume. To investigate whether plasma and renal ET-1 participate in the cardiovascular response to exercise-induced hypovolaemia, we studied changes in plasma and urinary ET-1 in healthy non-professional athletes after 2 h of jogging performed both without and with drinking isotonic fluids. After the run, which caused a 13% plasma volume (PV) reduction, plasma and renal ET-1 (+117% and +118%) increased significantly (all P < 0.01). Fluid loss restitution during the run significantly attenuated either the PV contraction (-1.2%) and plasma and renal ET-1 increase (+2 and +3%). At multiple regression analysis changes in AVP plasma concentration, and not in PRA or PV per se, were significantly related to ET-1 changes both in plasma and urine. The present findings indicate that both plasma and renal ET-1 participate in the cardiovascular response to hypovolaemia induced by long-lasting, dynamic exercise.

Topics: Adult; Blood Volume; Body Weight; Endothelin-1; Humans; Isotonic Solutions; Kidney; Male; Physical Exertion; Regression Analysis; Renin; Water-Electrolyte Balance

In type II diabetic patients, one can detect several pathologic changes including insulin resistance and hypertension. Sprague-Dawley rats fed a fructose-rich diet (group F) exhibited these characteristic abnormalities within 2 weeks and were an excellent laboratory animal model for research on insulin action and development of hypertension. Since fish oils containing omega-3 fatty acids have a beneficial effect in preventing atherosclerotic diseases, we performed repeated experiments to test the effects of fish oil supplementation in group F rats. Compared with control rats on a normal diet (group C), group F consistently developed hypertriglyceridemia without elevated plasma free fatty acid (FFA), fasting hyperinsulinemia together with fasting hyperglycemia (insulin resistance syndrome), and systolic hypertension within 3 weeks. Insulin-stimulated glucose uptake and insulin binding of adipocytes were significantly reduced. Rats fed the same high-fructose diet but supplemented with fish oil (group O) had alleviation of all of these metabolic defects and a normalized insulin sensitivity and blood pressure. beta-Cell function as shown by plasma glucose and insulin responses to oral glucose remained intact in group F and group O. The plasma endothelin-1 (ET-1) level and ET-1 binding to adipocytes were not different among the three groups. Based on these results, we suggest that dietary high fructose induced hypertriglyceridemia and insulin resistance with normal islet function, and that the induced hypertension was not associated with plasma ET-1 abnormalities and was probably caused by other undefined pathologic changes that can be prevented by dietary omega-3 fatty acids.

Topics: Adipocytes; Animals; Binding, Competitive; Blood Glucose; Blood Pressure; Body Weight; Cohort Studies; Diabetes Mellitus, Type 2; Dietary Supplements; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelin-1; Fish Oils; Fructose; Hypertension; Insulin; Insulin Resistance; Iodine Radioisotopes; Male; Rats; Rats, Sprague-Dawley; Time Factors

We sought to assess the effects of second-hand smoke (SHS) and gender on infarct size in young rats exposed in utero or in the neonatal to adolescent period, or both.. We previously demonstrated that exposure to SHS increases infarct size in a rat model of ischemia and reperfusion, with a dose-response relation. These results are consistent with epidemiologic studies demonstrating that SHS increases risk of death from heart disease.. Thirty-one pregnant female rats were randomly divided into two groups: those exposed to SHS and a control group (non-SHS). After 3 weeks, each rat had given birth to 10 to 12 rats. One hundred one neonatal rats were divided into four groups according to exposure to SHS in utero (SHSu) and randomized to SHS exposure in the neonatal to adolescent period (SHSna). After 12 weeks, all rats were subjected to 17 min of left coronary artery occlusion and 2 h of reperfusion.. Birth mortality was higher in the SHSu group than in the non-SHSu group (11.9% vs. 2.8%, p < 0.001). Body weight of neonatal rats at 3 and 4 weeks in the two SHSu groups was lower than that of rats in the two non-SHSu groups (p < 0.001). Exposure to SHSna increased endothelin-1 levels in plasma (p = 0.001). In all 70 young rats who survived the neonatal period, infarct size (Infarct mass/Risk area x 100%) was greater in the SHSna groups than in the non-SHSna groups (p = 0.005) and in the male groups than in the female groups (p < 0.001).. Exposure to SHS in the neonatal to adolescent period and male gender increased myocardial infarct size in a young rat model of ischemia and reperfusion. These results are consistent with epidemiologic studies demonstrating that SHS increases the health risk to neonates and adolescents.

Topics: Angiotensin II; Animals; Animals, Newborn; Body Weight; Endothelin-1; Female; Male; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Pregnancy; Prenatal Exposure Delayed Effects; Random Allocation; Rats; Rats, Sprague-Dawley; Risk Factors; Sex Factors; Tobacco Smoke Pollution

Renal effects of FR139317, an endothelin ETA receptor antagonist, were examined using anesthetized normotensive and deoxycorticosterone acetate (DOCA)-salt hypertensive rats. The intravenous bolus injection of FR139317 (10 mg/kg) produced a slight decrease in mean blood pressure (MAP; -13%) in the control rats and this hypotension was accompanied by a moderate renal vasodilation (renal vascular resistance: RVR; -12%). In the DOCA-salt hypertensive rat, FR139317 had a more pronounced hypotensive effect (MAP; -26%) accompanied by a potent renal vasodilation (RVR; -33%). FR139317 significantly increased renal blood flow only in the DOCA-salt rats. In contrast, FR139317 produced a significant decrease in urine flow and urinary sodium excretion only in control rats. Northern blot analysis revealed that the renal prepro endothelin-1 (ET-1) mRNA level was significantly increased in DOCA-salt hypertensive rats. Thus, it seems likely that endogenous ET-1 is responsible for the maintenance of DOCA-salt-induced hypertension. We also suggest that at least in part, ET-1 and ETA receptors are involved in renal hemodynamic abnormalities in DOCA-salt-induced hypertension. The augmentation of renal ET-1 production may possibly have a function in the development and maintenance of DOCA-salt-induced hypertension.

Topics: Animals; Azepines; Blood Pressure; Blotting, Northern; Body Weight; Desoxycorticosterone; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Hypertension, Renovascular; Indoles; Kidney; Male; Organ Size; Protein Precursors; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptors, Endothelin; Renal Circulation; RNA, Messenger

Abnormalities in the production of nitric oxide and endothelin-1 have been implicated in the development of preeclampsia. We postulated that long-term nitric oxide synthase inhibition with L-nitro-arginine methyl ester would induce sustained hypertension, a rise in plasma levels of endothelin-1, and fetal growth restriction.. Conscious virgin and pregnant Sprague-Dawley rats received infusions of vehicle or L-nitro-arginine methyl ester (2.5 mg/kg/hr) for 11 days. Mean arterial pressure was assessed serially. On day 21 of gestation (or equivalent in virgin rats) plasma was collected for endothelin-1 levels; pup weight and litter size were determined. Data were analyzed with analysis of variance and regression techniques.. Mean arterial pressure was constant in virgin control rats (n = 7) but declined in pregnant control rats (n = 11) as gestation advanced. Nitric oxide synthase inhibition in virgin (n = 10) and pregnant (n = 11) rats caused sustained elevations in mean arterial pressure (165 +/- 7 vs 100 +/- 3 mm Hg, L-nitro-arginine methyl ester vs control virgin rats, p < 0.0001; 149 +/- 5 vs 91 +/- 2 mm Hg, L-nitro-arginine methyl ester vs control pregnant rats, p < 0.0001). L-nitro-arginine methyl ester induced a rise in plasma endothelin-1 levels in virgin (4.4 +/- 0.1 vs 3.5 +/- 0.1 pg/ml, L-nitro-arginine methyl ester vs control, p < 0.0001) and pregnant rats (3.0 +/- 0.1 vs 2.6 +/- 0.1 pg/ml, L-nitro-arginine methyl ester vs control, p < 0.0001). Pregnant rats had lower endothelin-1 levels than did virgin rats (p < 0.0001). Mean arterial pressure and endothelin-1 were significantly correlated in pregnant rats. L-nitro-arginine methyl ester decreased pup weight (2.4 +/- 0.4 vs 3.7 +/- 0.2 gm/pup/litter, L-nitro-arginine methyl ester vs control, p < 0.01) and litter size (6.6 +/- 1.3 vs 10.2 +/- 0.9 pups/litter, L-nitro-arginine methyl ester vs control, p < 0.05).. Long-term nitric oxide synthase blockade causes sustained hypertension, elevated levels of endothelin-1, and fetal growth restriction. Although the endocrine and pressor effects are not unique to pregnancy, this model clearly induces some of the changes seen in preeclampsia and may be useful for studying specific interventions.

Topics: Animals; Blood Pressure; Body Weight; Embryonic and Fetal Development; Endothelin-1; Female; Hypertension; Litter Size; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Pregnancy; Pregnancy Complications, Cardiovascular; Pregnancy, Animal; Rats; Rats, Sprague-Dawley; Time Factors

The vasoactive peptides angiotensin II (Ang II) and endothelin-1 (ET-1) have been implicated in cardiac hypertrophy. This study investigates Ang II and ET-1 effects on intracellular free calcium concentration and the receptor subtype through which agonist-induced calcium responses are mediated in isolated cardiomyocytes and fibroblasts from hypertrophied hearts of spontaneously hypertensive rats (SHR). We measured intracellular free calcium concentration by fura 2 methodology and determined receptor status by radioligand binding assays. Ang II (10(-12) to 10(-7) mol/L) had no effect on cardiomyocyte calcium levels in control Wistar-Kyoto rats but significantly increased (P < .01) intracellular free calcium concentration in a dose-dependent manner in cardiomyocytes from SHR. Ang II total and specific binding were increased (P < .05) in SHR cardiomyocytes. Calcium responses elicited by 10(-7) to 10(-5) mol/L Ang II were significantly reduced (P < .01) in SHR fibroblasts despite no significant change in Ang II receptor density. The angiotensin type 1 receptor blocker losartan (1 mumol/L) blocked Ang II-stimulated calcium transients, whereas the angiotensin type 2 receptor blocker PD 123319 had no effect. ET-1- and sarafotoxin S6c-induced calcium responses in cardiomyocytes and fibroblasts were not different between hypertensive and control groups. In conclusion, Ang II and ET-1 elicit distinct and differential responses in a cell-specific manner in cardiomyocytes and fibroblasts from hypertrophied hearts of SHR. Whereas Ang II-mediated effects, which are elicited via angiotensin type 1 receptors, are detectable in cardiomyocytes from SHR, responses to Ang II are blunted in fibroblasts from SHR, and ET-1-related actions are similar in cells from both rat groups. Stimulation of cardiomyocytes by Ang II in hypertrophied hearts associated with pressure overload in genetic hypertension suggests that Ang II could modulate the function of cardiomyocytes of SHR but not those of Wistar-Kyoto rats, whereas cardiac actions of ET-1 do not change with the development of hypertension.

Topics: Angiotensin II; Animals; Antihypertensive Agents; Biphenyl Compounds; Blood Pressure; Body Weight; Calcium; Endothelin-1; Fibroblasts; Heart; Imidazoles; Losartan; Male; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptors, Angiotensin; Species Specificity; Tetrazoles; Vasoconstrictor Agents; Viper Venoms

Deoxycorticosterone acetate (DOCA)-salt hypertensive rats exhibit a very severe degree of cardiovascular hypertrophy, which may in part be mediated by overexpression of the endothelin-1 gene.. To examine the effects of the angiotensin I converting enzyme inhibitor cilazapril and of the calcium channel antagonist mibefradil, both of which may affect potential mechanisms responsible for hypertrophy of cardiovascular structures, and that of the nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME), which may exert a paradoxical inhibitory effect on cardiovascular growth, on the severe cardiovascular hypertrophy of DOCA-salt hypertensive rats and on arterial expression of the endothelin-1 gene.. Small-artery structure was examined on a wire myograph and endothelin-1 messenger RNA (mRNA) was quantified by Northern blot analysis.. Cilazapril did not affect blood pressure, cardiovascular structure or the increased abundance of endothelin mRNA of DOCA-salt hypertensive rats. Mibefradil treatment resulted in lower blood pressure, reduced cardiac hypertrophy, near-normal structure of conduit and small arteries and lower endothelin-1 mRNA abundance. L-NAME treatment resulted in higher blood pressure and increased severity of conduit artery hypertrophy, but reduced cardiac and small artery hypertrophy, and enhanced aortic endothelin-1 mRNA.. These results suggest that the renin-angiotensin system does not play a role in cardiovascular hypertrophy in DOCA-salt hypertensive rats, which is not unexpected since plasma renin is suppressed in these rats. Calcium channel blockade may interfere with mechanisms underlying vascular hypertrophy in this model via blockade of calcium entry or by reducing vascular endothelin-1 gene expression when the blood pressure is lowered. L-NAME has been shown to exert a growth-inhibitory effect on small arteries and on the heart despite increasing blood pressure, probably independently from its ability to inhibit nitric oxide synthase, the latter of which is presumably involved in the blood pressure rise induced.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Arteries; Blood Pressure; Body Weight; Calcium Channel Blockers; Cardiomegaly; Cilazapril; Desoxycorticosterone; Endothelin-1; Hypertension; NG-Nitroarginine Methyl Ester; Nifedipine; Organ Size; Rats; Rats, Sprague-Dawley; Renin

1. The aim of the study was to visualize endothelin-1 (ET-1)-mediated constriction in renal vessels of cortical and juxtamedullary glomeruli in the split hydronephrotic rat kidney in vivo and to functionally characterize the ET receptor subtypes involved. 2. ET-1 (10(-9) M) constricted preglomerular vessels (by 6-18%) and efferent arterioles (by 11-13%), and decreased glomerular blood flow (GBF, by 55%) of cortical and juxtamedullary glomeruli. 3. The ETA antagonist BQ-123 (10(-6) M), as well as the ETB antagonist BQ-788 (2 x 10(-7) M) and IRL 1038 (10(-6) M), shifted the concentration-response curve of GBF for ET-1 to the right by one order of magnitude. While BQ-123 antagonized ET-1 constriction only in preglomerular vessels, BQ-788 and IRL 1038 were effective both in preglomerular vessels and efferent arterioles. 4. The ETB agonist IRL 1620 (10(-8) M) reduced GBF by 50% and constricted efferent arterioles (by 20-33%) about two times more than preglomerular vessels (by 6-14%). 5. Our results suggest that in renal cortical and juxtamedullary vessels of rats, ET-1-induced preglomerular vasoconstriction is mediated by ETA and ETB receptors, while efferent vasoconstriction is predominantly mediated by ETB receptors, which might have important consequences for the regulation of glomerular filtration pressure by ET.

Topics: Animals; Blood Pressure; Body Weight; Disease Models, Animal; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Female; Glomerular Filtration Rate; Kidney; Kidney Glomerulus; Microcirculation; Nephrosis; Peptide Fragments; Peptides, Cyclic; Rats; Rats, Wistar; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Vasoconstriction

Alpha-naphthylthiourea when injected intraperitoneally to rats (10 mg kg-1 i.p.) produced lung oedema as indicated by an increase in lung weight/body ratio and pleural effusion reaching a maximum within 4 hours. Prior intravenous single bolus injection of endothelin-1 elicited a significant and dose-dependent inhibition in both parameters. However, prior i.v. injection of angiotensin II using relatively higher doses did not alter the oedema-producing effect of alpha-naphthylthiourea indicating a characteristic for endothelin-1. The inhibitory effect of endothelin-1 on pleural effusion is more prominent than lung weight/body weight ratio. The resolution of lung oedema by single bolus i.v. injection of endothelin-1 is probably due to the acute long-lasting and potent vasoconstrictor effect of the peptide and its large accumulation in lung tissue. Phosphoramidon, an inhibitor of endothelin converting enzyme, did not alter the oedema producing effect of alpha-naphthylthiourea indicating the lack of the participation of endothelin-peptide cascade to this pathological event. Bosentan, a non-selective receptor blocker of endothelin-1, did not inhibit the preventive effect of the peptide against alpha-naphthylthiourea-induced lung oedema. Possible mechanisms of the acute effect of endothelin-1 on lung oedema are discussed.

Topics: Angiotensin II; Animals; Aspartic Acid Endopeptidases; Body Weight; Bosentan; Endothelin-1; Endothelin-Converting Enzymes; Glycopeptides; Male; Metalloendopeptidases; Organ Size; Pleural Effusion; Protease Inhibitors; Pulmonary Edema; Rats; Sulfonamides; Thiourea

To examine potential intracellular signalling abnormalities of endothelin-1 (ET-1) and vasopressin (AVP) which may contribute to blood pressure elevation, contractility and inositol phosphate levels in intact arteries and calcium transients in vascular smooth muscle cells were investigated after stimulation with these peptides in pre-hypertensive 5 week-old spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto (WKY) rats. Contractility of aorta in response to ET-1, AVP and norepinephrine (NE) was blunted in SHR relative to WKY. Contraction of mesenteric resistance arteries induced by ET-1 was similar in both groups, whereas sensitivity in response to NE and AVP was greater in SHR. Basal inositol phosphate in aorta and mesenteric arteries was elevated in SHR, but ET-1 and AVP-stimulated inositol phosphate responses were similar in both groups. Calcium transients induced by ET-1 and AVP in vascular smooth muscle cells were similar in young SHR and WKY. In contrast, in adult rats inositol phosphate responses to ET-1 were blunted in aorta of SHR, but were normal in mesenteric arteries. Inositol phosphate responses to AVP were similar in both rat strains of rats both in aorta and mesenteric arteries except for accumulation of inositol trisphosphate, which was enhanced in mesenteric arteries of SHR. Calcium mobilization in vascular smooth muscle cells from adult SHR also exhibited enhanced responses to AVP. In conclusion, in young SHR, blunted ET-1 and AVP-induced contraction in aorta and enhanced AVP-induced mesenteric artery contraction are associated with normal inositol phosphate production and calcium mobilization. Signal transduction in response to ET-1 and AVP is depressed in aorta of pre-hypertensive SHR after the step of inositol phosphate generation and calcium mobilization. Resistance vessel reactivity to AVP is enhanced in young SHR at steps following inositol phosphate generation and calcium mobilization. These results argue against a role of ET-1, but suggest the possible involvement of AVP in the development of this model of genetic hypertension.

Topics: Aging; Animals; Antibodies; Aorta; Arginine Vasopressin; Blood Pressure; Body Weight; Calcium; Cells, Cultured; Dose-Response Relationship, Drug; Endothelin-1; Male; Mesenteric Arteries; Muscle, Smooth, Vascular; Norepinephrine; Phosphatidylinositols; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Signal Transduction; Tritium; Type C Phospholipases; Vasoconstriction; Vasoconstrictor Agents

In previous studies it has been shown that blood vessels of deoxycorticosterone acetate (DOCA) salt hypertensive rats present significantly higher immunoreactive ET-1 (ir-ET-1) content and increased ET-1 gene expression. DOCA-salt hypertensive rats respond to treatment with the combined ETA/ETB endothelin receptor antagonist bosentan with lowering of blood pressure. In the present study, we investigated the ir-ET-1 levels and the expression of the ET-1 gene in blood vessels of DOCA-salt hypertensive rats treated or not treated with bosentan. Blood pressure was significantly lower in bosentan-treated rats (185 +/- 6 mmHg; 1 mmHg = 133.3 Pa) compared with DOCA-salt hypertensive rats (203 +/- 4 mmHg; p < 0.01). Plasma ir-ET-1 concentration was slightly but significantly elevated (p < 0.01) in DOCA-salt hypertensive rats compared with uninephrectomized control rats, and was further increased (p < 0.01) in bosentan-treated rats. The tissue wet weight and ir-ET-1 content of segments of thoracic aorta were significantly increased (p < 0.01) in DOCA-salt hypertensive rats in comparison with control rats, but were similar in bosentan-treated DOCA-salt rats. The abundance of ET-1 mRNA measured by Northern blot analysis in thoracic aorta and the ir-ET-1 content were attenuated by bosentan treatment. Tissue wet weight and ir-ET-1 content in the mesenteric vascular bed were similar in bosentan-treated and -untreated DOCA-salt rats, and were significantly higher in both groups than in control rats (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Base Sequence; Blood Pressure; Blood Vessels; Blotting, Northern; Body Weight; Bosentan; Desoxycorticosterone; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Hypertension; Male; Molecular Sequence Data; Polymerase Chain Reaction; Protein Precursors; Rats; Rats, Sprague-Dawley; RNA Probes; RNA-Directed DNA Polymerase; Sulfonamides

Vasoconstrictor responses to 5-hydroxytryptamine (5-HT), alpha-methyl-5-HT, endothelin-1, arachidonic acid and the thromboxane A2-mimetic U46619 ((15S)-hydroxy-11 alpha, 9 alpha-(epoxymethano)prosta-5Z,13E-dienoic acid) were obtained in blood-perfused hindquarters of 6-week streptozotocin-diabetic rats. When compared to responses obtained in hindquarters of control rats, responses to 5-HT, alpha-methyl-5-HT, and arachidonic acid were attenuated in hindquarters of diabetic rats. However, responses to endothelin-1 or U46619 were not significantly different between controls and diabetics. These results suggest that 5-HT2, but not endothelin ETA receptor-mediated responses are reduced in hindquarters of diabetic rats. The results utilising arachidonic acid and U46619 suggest that there may also be a defect in the cyclo-oxygenase cascade during diabetes.

Topics: Animals; Arachidonic Acid; Blood Glucose; Blood Pressure; Body Weight; Diabetes Mellitus, Experimental; Endothelin-1; Heart Rate; Hindlimb; Hypoglycemic Agents; In Vitro Techniques; Insulin; Ketanserin; Male; Perfusion; Rats; Rats, Wistar; Receptors, Serotonin; Regional Blood Flow; Serotonin; Serotonin Antagonists; Serotonin Receptor Agonists