endothelin-1 and Hypercholesterolemia

The aim of this review article is to summarize the current knowledge about mechanisms that connect blood pressure regulation and hypercholesterolemia, the mutual interaction between hypertension and hypercholesterolemia, and their influence on atherosclerosis development. Our research shows that at least one-third of the population of Western Europe has hypertension and hypercholesterolemia. Several biohumoral mechanisms could explain the relationship between hypertension and hypercholesterolemia and the association between these risk factors and accelerated atherosclerosis. The most investigated mechanisms are the renin-angiotensin-aldosterone system, oxidative stress, endothelial dysfunction, and increased production of endothelin-1. Arterial hypertension is frequently observed in combination with hypercholesterolemia, and this is related to accelerated atherosclerosis. Understanding the mechanisms behind this relationship could help explain the benefits of therapy that simultaneously reduce blood pressure and cholesterol levels.

Topics: Antihypertensive Agents; Atherosclerosis; Blood Pressure; Endothelin-1; Endothelium, Vascular; Humans; Hypercholesterolemia; Hypertension; Hypolipidemic Agents; Inflammation Mediators; Lipids; Muscle, Smooth, Vascular; Oxidative Stress; Renin-Angiotensin System; Risk Factors

The vascular endothelium synthesizes and releases a spectrum of vasoactive substances and therefore plays a fundamental role in the basal and dynamic regulation of the circulation. Nitric oxide (NO)-originally described as endothelium-derived relaxing factor-is released from endothelial cells in response to shear stress produced by blood flow, and in response to activation of a variety of receptors. After diffusion from endothelial to vascular smooth muscle cells, NO increases intracellular cyclic guanosine-monophosphate concentrations by activation of the enzyme guanylate cyclase leading to relaxation of the smooth muscle cells. NO has also antithrombogenic, antiproliferative, leukocyte-adhesion inhibiting effects, and influences myocardial contractility. Endothelium-derived NO-mediated vascular relaxation is impaired in spontaneously hypertensive animals. NO decomposition by free oxygen radicals is a major mechanism of impaired NO bioavailability. The resulting imbalance of endothelium-derived relaxing and contracting substances disturbs the normal function of the vascular endothelium. Endothelin acts as the natural counterpart to endothelium-derived NO. Besides its arterial blood pressure rising effect in humans, endothelin-1 induces vascular and myocardial hypertrophy, which are independent risk factors for cardiovascular morbidity and mortality. Current therapeutic strategies concentrate mainly on lowering low-density lipoprotein cholesterol and an impressive reduction in the risk for cardiovascular morbidity and mortality has been achieved. Inflammatory mechanisms play an important role in vascular disease and inflammatory plasma markers correlate with prognosis. The production of reactive oxygen species under pathological conditions may represent an important inflammatory trigger. Novel therapeutic strategies specifically targeting inflammation thus bear great potential for the prevention and treatment of atherosclerotic vascular disease. In this context, the vascular actions of flavanol-rich cocoa, particularly with regard to enhanced NO synthesis and endothelial function observed in humans following consumption, warrants further attention. This review discusses pharmacological and dietary intervention.

Topics: Adrenergic beta-Antagonists; Angiotensin-Converting Enzyme Inhibitors; Arginine; Atherosclerosis; Biopterins; Cacao; Calcium Channel Blockers; Cyclooxygenase Inhibitors; Dyslipidemias; Endothelin-1; Endothelins; Endothelium, Vascular; Flavonoids; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypercholesterolemia; Lipoproteins, HDL; Nitric Oxide; Oxidative Stress; Reactive Oxygen Species

Increased evidence has shown that endothelin-1 (ET-1) derived from the arterial cells is involved in the development of atherosclerosis. ET-1 and ET receptors are upregulated in both human and experimental animal atherosclerotic lesions. Plasma ET-1 levels are significantly elevated in hypercholestolemic subjects and cholesterol-fed animals. We hypothesized that plasma lipoproteins such as LDL and HDL retained in the arterial wall can affect ET-1 production and secretion, thereby sustaining vascular functions. Using a two-chamber culture system, we have demonstrated that endothelial cells (ECs) show a polar secretion of ET-1; the majority of ET-1 are secreted toward the basal side of the vessels. Furthermore, we found that LDL enhances whereas HDL inhibits the ET-1 secretion from ECs in a polarized pattern. In order to demonstrate ET receptor distribution in the lesion, we recently studied both human and apoE-KO mice. Our study showed that there is an increased expression of ETB receptors in foamy macrophages in the lesions. More importantly, medial smooth muscle cells (SMCs) beneath the foam cell lesions exhibited a higher intensity of ETB receptor immunoreactivity than those located in foam cell-free areas. In such an area, ET-1 immunoreactivity is also increased. These results suggest that accumulation of foamy macrophages may modulate the shift of ET receptor subtypes from ETA to ETB in SMCs and an enhanced ET system mediated by ETB receptors may play a pivotal role in the progression of atherosclerosis. This notion has been further supported by a recent finding that administration of ET receptor antagonists resulted in a significant reduction of atherosclerosis in apoE-KO mice.

Topics: Animals; Arteriosclerosis; Endothelin Receptor Antagonists; Endothelin-1; Humans; Hypercholesterolemia; Mice; Receptors, Endothelin

Endothelial health is a key factor in normal cardiovascular homeostasis, and recent studies have revealed several important functions of the vascular endothelium that protect against atherothrombosis. These include control over arterial tone, coagulation, fibrinolysis, and vascular growth. Consequently, endothelial dysfunction has been implicated as an important event in the pathogenesis of atherosclerosis, coronary vasoconstriction, hypertension, and myocardial ischaemia. Therefore, there has been considerable research interest in diagnostic assays for the assessment of endothelium. This review outlines the current status of markers of endothelial dysfunction, particularly those related to vasomotor control, as well as circulating markers of vascular health.

Topics: Adult; Aged; Arteriosclerosis; Biomarkers; Child; Confidence Intervals; Coronary Disease; Endothelin-1; Endothelium, Vascular; Humans; Hypercholesterolemia; Hypertension; Nitric Oxide; Plethysmography; Prognosis; Risk; Risk Factors; Tissue Plasminogen Activator; Tomography, Emission-Computed; Vasodilation; Vasomotor System; von Willebrand Factor

Endothelin (ET)-1, a potent vasoconstrictor peptide, is primarily released abluminally from endothelial cells and exerts its biological effect through the activation of specific ET receptors. Endothelin subtype A receptors (ET(A)) are involved in constriction and proliferation of vascular smooth muscle cells, whereas endothelin subtype B receptors (ET(B)) on endothelial cells mediate the formation of nitric oxide, which acts as vasodilator and inhibits platelet aggregation. Cardiovascular risk factors such as hypertension and aging, as well as hypercholesterolemia, which are precursors of atherosclerosis, and elevated ET-1 levels are found. The best approach to determine the contribution of endogenous ET to vascular structural and functional alterations can be achieved by chronic inhibition of ET receptors with ET receptor antagonists. Recent studies showed favourable effects of selective ET(A)-antagonists on vascular alterations in different experimental models of hypertension, hypercholesterolemia and atherosclerosis, suggesting that activation of the local ET system importantly contributes to endothelial dysfunction and vascular remodeling, mainly through ET(A) receptors. Chronic blockade of ET(A) receptors may be a new therapeutic approach for the treatment of atherosclerosis and its risk factors.

Topics: Aging; Arteriosclerosis; Endothelin Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Humans; Hypercholesterolemia; Hypertension; Receptors, Endothelin; Risk Factors; Vasoconstriction

Erectile dysfunction (ED) is a common problem, particularly in older men. The production of penile erection involves an interplay between autonomic nerves and locally released vasoactive mediators. Endothelin-1 (ET-1) is a peptide released from endothelium in the corpus cavernosum, which causes smooth muscle contraction. Recent studies have investigated the physiological significance of ET-1 in the control of erectile function and it may play a role in detumescence. There is also much evidence to link ET-1 to risk factors for ED. ET-1 antagonists may prove beneficial in the treatment of ED and also in prevention of long term deterioration of erectile function. These antagonists may also find a role when used in combination with agents, which are established for the treatment of ED.

Topics: Animals; Antihypertensive Agents; Bosentan; Diabetes Complications; Diabetes Mellitus; Endothelin-1; Erectile Dysfunction; Humans; Hypercholesterolemia; Hypertension; Male; Myocardial Ischemia; Neural Pathways; Nitric Oxide; Penile Erection; Risk Factors; Smoking; Sulfonamides

There is convincing evidence that the prevalence of erectile dysfunction is increased among men with ischaemic heart disease. This association may be attributed to the fact that both erectile dysfunction and ischaemic heart disease share similar risk factors (e.g. hypertension, dyslipidaemia, diabetes and smoking). Nitric oxide (NO) activity is adversely affected, in penile and vascular tissue, by these risk factors. It is therefore not surprising that a defect in NO activity is thought to play a role in the pathogenesis of both erectile dysfunction and ischaemic heart disease. We consider this evidence and propose that defective NO activity provides a unifying explanation for the association between these two conditions. Further research in this area may improve our understanding of the pathogenesis of cardiovascular diseases as a whole.

Topics: Cardiovascular Diseases; Diabetes Mellitus; Endothelin-1; Humans; Hypercholesterolemia; Male; Muscle, Smooth, Vascular; Nitric Oxide; Penile Erection; Penis

Experimental and clinical studies have demonstrated the effect of phytosterols (PS) on reducing plasma levels of cholesterol and LDL-c, but the effects of plant sterols beyond cholesterol-lowering are still questionable. Since inflammation and endothelial dysfunction are involved in the pathogenesis of atherosclerosis, this study aims to evaluate the effect of PS on biomarkers involved in atherosclerosis progression and whether these effects are independent of alterations in plasma LDL-c levels. Thirty-eight moderately hypercholesterolemic volunteers (58 ± 12 years; LDL-c ≥ 130 mg/dL) were randomly assigned to consume 400 mL/day of soy milk or soy milk + PS (1.6 g/day) for 4 weeks in a double-blind, placebo-controlled, cross-over study. Blood samples were collected and lipid profiles and biomarkers for inflammation and endothelial dysfunction determined. The results showed that PS treatment reduced endothelin-1 plasma concentration by 11% (

Topics: Adult; Aged; Apolipoproteins B; Atherosclerosis; Biomarkers; Brazil; C-Reactive Protein; Cholesterol; Cholesterol, LDL; Cross-Over Studies; Dietary Supplements; Double-Blind Method; Endothelin-1; Female; Humans; Hypercholesterolemia; Inflammation; Lipids; Male; Middle Aged; Phytosterols; Plasma; Soy Milk; Sterols; Triglycerides

This study tested the hypothesis that pioglitazone reduces endothelin-1 activity in the forearm vasculature in non-diabetic patients with hypertension or hypercholesterolemia and variable degrees of insulin resistance.. We conducted a single center, randomized, double-blind, placebo controlled, cross-over trial in 80 patients with either hypertension or hypercholesterolemia and further classified as insulin-sensitive or insulin-resistant based on a published insulin sensitivity index. Participants received pioglitazone 45 mg daily or matching placebo for eight weeks. The main endpoint was the change in forearm vascular endothelin-1 activity, as assessed by intra-arterial infusion of the endothelin type A receptor blocker BQ-123, measured at the end of each 8-week treatment period.. Pioglitazone lowered plasma insulin (P < 0.001), improved insulin sensitivity (P < 0.001), increased HDL (P < 0.001), and reduced triglycerides (P = 0.003), free fatty acids (P = 0.005), and C-reactive protein (P = 0.001). However, pioglitazone did not affect the vasodilator response to BQ-123 in the whole group (P = 0.618) and in the diagnosis or insulin sensitivity subgroups. Hence, in non-diabetic patients with hypertension or hypercholesterolemia, PPARγ activation with pioglitazone does not affect endothelin-1 activity, despite enhancing insulin sensitivity and reducing plasma insulin and C-reactive protein levels.. In non-diabetic patients with hypertension or hypercholesterolemia, pioglitazone improves insulin sensitivity, lipid profile, and inflammation but does not affect endothelin activity. Our data suggest that the determinants of endothelin-1 vascular activity in vivo may differ and/or be more complex than those suggested by the results of previous in vitro studies.

Topics: Biomarkers; C-Reactive Protein; Cross-Over Studies; District of Columbia; Double-Blind Method; Endothelin A Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Fatty Acids, Nonesterified; Forearm; Humans; Hypercholesterolemia; Hypertension; Insulin; Insulin Resistance; Lipoproteins, HDL; Peptides, Cyclic; Pioglitazone; PPAR gamma; Thiazolidinediones; Time Factors; Treatment Outcome; Triglycerides; Vasodilation

Polyunsaturated fatty acids (PUFA) have beneficial effects on cardiovascular risk, although the mechanisms are incompletely understood. In a previous article, we showed significant reductions in low-density lipoprotein cholesterol and several markers of inflammation with increasing intake of alpha-linolenic acid (ALA) from walnuts and flax.. To examine effects of ALA on cardiovascular responses to acute stress, flow-mediated dilation (FMD) of the brachial artery, and blood concentrations of endothelin-1 and arginine-vasopressin (AVP).. Using a randomized, crossover study design, cardiovascular responses to acute stress were assessed in 20 hypercholesterolemic subjects, a subset of whom also underwent FMD testing (n  =  12). Participants were fed an average American diet (AAD) and 2 experimental diets that varied in the amount of ALA and linoleic acid (LA) that they contained. The AAD provided 8.7% energy from PUFA (7.7% LA, 0.8% ALA). On the LA diet, saturated fat was reduced, and PUFA from walnuts and walnut oil provided 16.4% of energy (12.6% LA, 3.6% ALA). On the ALA diet, walnuts, walnut oil, and flax oil provided 17% energy from PUFA (10.5% LA, 6.5% ALA).. The ALA and LA diets significantly reduced diastolic blood pressure (-2 to -3 mm Hg) and total peripheral resistance (-4%), and this effect was evident at rest and during stress (main effect of diet, p < 0.02). FMD increased (+34%) on the diet containing additional ALA. AVP also increased by 20%, and endothelin-1 was unchanged.. These results suggest novel mechanisms for the cardioprotective effects of walnuts and flax, and further work is needed to identify the bioactives responsible for these effects.

Topics: alpha-Linolenic Acid; Biomarkers; Blood Pressure; Cardiovascular Diseases; Cholesterol, LDL; Cross-Over Studies; Diet; Endothelin-1; Flax; Humans; Hypercholesterolemia; Juglans; Linoleic Acid; Middle Aged; Nuts; Plant Oils; Risk Factors; Stress, Psychological; Vascular Resistance

Essential hypertension is associated with enhanced biological activity of endothelin-1 (ET-1) and impaired endothelium-dependent vasodilatation. Dihydropyridine calcium antagonists have antioxidant activity in vitro, and they improve endothelial function in vivo. We tested whether calcium antagonists also influence the biological activity of ET-1 in essential hypertensive (EH) patients in the presence and absence of hypercholesterolemia. In 9 healthy subjects (normotensive [NT] subjects, age: 48.3+/-7.6 years; blood pressure: 118+/-8.6/69+/-5.4 mm Hg) and 21 EH subjects (age: 50.0+/-7.8 years; blood pressure: 164.4+/-5.4/103.8+/-4.4 mm Hg), we studied forearm blood flow and its modification induced by intrabrachial administration of ET-1, phenylephrine, acetylcholine, and sodium nitroprusside at baseline and after 24 weeks of treatment with a nifedipine gastrointestinal therapeutic system (30 to 60 mg per day). At baseline, the first dose of ET-1 (0.5 microg/100 mL of forearm tissue per minute) caused a slight vasodilatation in NT but not in EH subjects, whereas the following higher doses caused a comparable dose-dependent vasoconstriction in EH and NT subjects. The effect of acetylcholine was significantly reduced in EH as compared with NT subjects. In contrast, sodium nitroprusside and phenylephrine had similar effects in NT and EH subjects. After chronic treatment with the nifedipine gastrointestinal therapeutic system, the vasoconstrictor effect induced by both ET-1 and phenylephrine was significantly blunted, whereas the response to acetylcholine was significantly increased and the vasodilation to sodium nitroprusside unchanged. Hypercholesterolemic EH subjects showed a further reduced response to acetylcholine compared with normocholesterolemic EH subjects, and the nifedipine gastrointestinal therapeutic system restored the vasodilation to acetylcholine in this subgroup. In conclusion, in EH subjects, chronic treatment with a long-acting dihydropyridine calcium antagonist not only exhibits a blood pressure-lowering effect but also reduces ET-1-induced vasoconstriction and improves endothelium-dependent vasodilation. Those vasculoprotective effects may importantly contribute to a reduction in major clinical events seen during treatment with these compounds.

Topics: Acetylcholine; Adult; Brachial Artery; Calcium Channel Blockers; Delayed-Action Preparations; Dose-Response Relationship, Drug; Drug Administration Schedule; Endothelin-1; Female; Forearm; Humans; Hypercholesterolemia; Hypertension; Injections, Intra-Arterial; Male; Middle Aged; Nifedipine; Phenylephrine; Regional Blood Flow; Vasoconstriction; Vasoconstrictor Agents; Vasodilator Agents

There is some controversy regarding whether vascular responses to endothelin are altered in hypercholesterolemia. Studies performed to date have been compromised by the use of endothelin antagonists at inappropriate concentrations. In the current study, we examine the role of endothelin-1 in hypercholesterolemic patients using lower, more selective doses of specific endothelin antagonists. Twenty-two patients with hypercholesterolemia (total plasma cholesterol > 6.0 mmol/l) and 17 healthy controls were recruited. Forearm vascular responses to endothelin-1 (5 pmol/min), the endothelin A antagonist BQ-123 (10 nmol/min), and the endothelin B antagonist BQ-788 (1 nmol/min) were obtained. Endothelin-1 caused a significant vasoconstriction in both hypercholesterolemic and control subjects, an effect that was not significantly different between the two groups (P = 0.784). BQ-123 caused a significant vasodilatation that was not significantly different between the two groups (P = 0.899). Similarly, responses to BQ-788 (P = 0.774) and mean plasma endothelin-1 levels were not different (control vs. hypercholesterolemia, 1.16 +/- 0.18 vs. 1.06 +/- 0.15 fmol/ml; P = 0.64). Responses to neither exogenous nor endogenous endothelin are influenced by plasma cholesterol levels in humans. It is thus unlikely that the endothelin system contributes to early vascular disease pathology in patients with hypercholesterolemia.

Topics: Blood Pressure; Endothelin-1; Female; Humans; Hypercholesterolemia; Male; Middle Aged; Receptor, Endothelin A; Receptor, Endothelin B; Regional Blood Flow

Hypercholesterolemia is a hazard for increasing susceptibility of the heart to myocardial infarction (MI) by inducing platelet hyperaggregability. Clopidogrel and prasugrel have documented cardioprotective effects in clinical studies. Herein, we investigated whether clopidogrel and prasugrel could protect against isoproterenol-induced acute MI (A-MI) under hypercholesterolemic conditions in rats.. Dietary hypercholesterolemic rats were subjected to acute doses of isoproterenol. Serum lipids, inflammatory markers, aortic endothelin1 and endothelial nitric oxide synthase (eNOS) mRNAs expression and immunexpression of BCL2 were determined.. Hypercholesterolemic rats showed infiltration of inflammatory cells and reduction in aortic wall thickness, deposition of fibrous tissue between cardiac muscle fibers. Protective doses of prasugrel or clopidogrel for 28 days before A-MI increased survival, amended the ECG parameters -including ST segment elevation- and improved the histopathological picture in hypercholesterolemic rats. This was coupled with reductions in platelet aggregation, creatine kinase-MB activity, endothelin 1, systemic inflammation and cardiac lipid peroxidation and increment in aortic eNOS expression. Clopidogrel and prasugrel groups showed enhanced BCL2 expression in cardiac fibers and aortic wall.. Prasugrel and clopidogrel protected against A-MI via anti-aggregatory and anti-inflammatory effects. These results add to the value of these drugs in correcting cardiovascular dysfunction in patients vulnerable to A-MI after confirmation by appropriate human studies.

Topics: Animals; Cardiovascular System; Clopidogrel; Creatine Kinase, MB Form; Endothelin-1; Gene Expression Regulation; Hypercholesterolemia; Male; Models, Animal; Mortality; Myocardial Infarction; Nitric Oxide Synthase Type III; Platelet Aggregation; Platelet Aggregation Inhibitors; Prasugrel Hydrochloride; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Wistar; Signal Transduction; Treatment Outcome

Coronary microvascular dysfunction (CMD) has been proposed as an important component of diabetes mellitus (DM)- and hypercholesterolemia-associated coronary artery disease (CAD). Previously we observed that 2.5 mo of DM and high-fat diet (HFD) in swine blunted bradykinin (BK)-induced vasodilation and attenuated endothelin (ET)-1-mediated vasoconstriction. Here we studied the progression of CMD after 15 mo in the same animal model of CAD. Ten male swine were fed a HFD in the absence (HFD, n = 5) or presence of streptozotocin-induced DM (DM + HFD, n = 5). Responses of small (∼300-μm-diameter) coronary arteries to BK, ET-1, and the nitric oxide (NO) donor S-nitroso-N-acetylpenicillamine were examined in vitro and compared with those of healthy (Normal) swine (n = 12). Blood glucose was elevated in DM + HFD (17.6 ± 4.5 mmol/l) compared with HFD (5.1 ± 0.4 mmol/l) and Normal (5.8 ± 0.6 mmol/l) swine, while cholesterol was markedly elevated in DM + HFD (16.8 ± 1.7 mmol/l) and HFD (18.1 ± 2.6 mmol/l) compared with Normal (2.1 ± 0.2 mmol/l) swine (all P < 0.05). Small coronary arteries showed early atherosclerotic plaques in HFD and DM + HFD swine. Surprisingly, DM + HFD and HFD swine maintained BK responsiveness compared with Normal swine due to an increase in NO availability relative to endothelium-derived hyperpolarizing factors. However, ET-1 responsiveness was greater in HFD and DM + HFD than Normal swine (both P < 0.05), resulting mainly from ET

Topics: Animals; Bradykinin; Coronary Vessels; Diabetes Mellitus, Experimental; Diet, High-Fat; Endothelin-1; Hypercholesterolemia; Intermediate-Conductance Calcium-Activated Potassium Channels; Large-Conductance Calcium-Activated Potassium Channels; Male; Microvessels; Nitric Oxide; Plaque, Atherosclerotic; Real-Time Polymerase Chain Reaction; Receptor, Endothelin A; Receptor, Endothelin B; S-Nitroso-N-Acetylpenicillamine; Small-Conductance Calcium-Activated Potassium Channels; Sus scrofa; Swine; Vasoconstriction; Vasodilation; Vasodilator Agents

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

Most clinical trials with vitamin E could not lower cholesterol and thus, have been deemed unsuccessful. Recently, tocotrienols, isomers of vitamin E have been found to lower LDL levels. To explore if tocotrienols could be the drug target for vitamin E, rabbits were kept on cholesterol diet for 60 days supplemented with tocotrienol-α, tocotrienol-δ, and tocotrienol-γ for the last 30 days. The serum cholesterol levels (in mmol/l) were 24.4 (tocotrienol-α), 34.9 (tocotrienol-δ), 19.8 (tocotrienol-γ) vs. 39.7 (control). Left ventricular function including aortic flow and developed pressure exhibited significantly improved recovery with tocotrienol-γ and -α, but not with tocotrienol-δ. The myocardial infarct size showed a similar pattern: 33% (tocotrienol-α), 23% (tocotrienol-γ), and 47% (tocotrienol-δ). To examine the molecular mechanisms of cardioprotective effects, gene expression profile was determined using Atlas 1.2/1.2II followed by determination of gene profiles using PedQuest 8.3 software. Based on genomic profiles, the following cholesterol-related proteins were examined: FABP, TGF-β (cholesterol suppresses TGF-β), ET-1 (increased by hypercholesterolemia), SPOT 14 (linked with hypercholesterolemia), and matrix metalloproteinase (MMP) 2 and MMP9 (cholesterol regulates MMP2 and MMP9 expression) in the heart. Consistent with the cardioprotective effects of tocotrienol-α and -γ, these two isomers reduced ET-1, decreased MMP2 and MM9, increased TGF-β and reduced SPOT 14, while tocotrienol-δ had no effects. The results of the present study demonstrate that the two isomers of tocotrienols, α and γ, render the hypercholesterolemic hearts resistant to ischemic reperfusion injury by lowering several hypercholesterolemic proteins including MMP2, MMP9, ET-1, and SPOT 14 and upregulating TGF-β.

Topics: Animals; Anticholesteremic Agents; Atherosclerosis; Cardiotonic Agents; Cholesterol; Chromans; Diet, High-Fat; Endothelin-1; Female; Gene Expression; Gene Expression Profiling; Heart; Hypercholesterolemia; In Vitro Techniques; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Myocardial Reperfusion Injury; Myocardium; Rabbits; Rats; Rats, Sprague-Dawley; Receptors, Estrogen; Sex Factors; Transforming Growth Factor beta; Vitamin E

Lipid-apheresis (LA) is thought to improve microcirculation. However, limited data are available on the effects on peripheral microcirculation. We investigated upper limb microcirculation of 22 patients undergoing regular LA on a weekly basis before and after LA. Using standardized semiquantitative scales, we analyzed blood flow, vasomotor function, and erythrocyte aggregation by capillary microscopy. In addition, capillary blood flow in quiescence and under heat and cryo-stress was evaluated by photoplethysmographic and laser Doppler anemometry. Moreover, levels of vasoactive mediators adrenalin, noradrenalin, endothelin-1 (ET-1), atrial natriuretic peptide (ANP), asymmetrical dimethyl-arginine (ADMA), as well as total protein and fibrinogen were measured. We found a significant increase in blood flow, the number of perfused capillaries and an improvement of erythrocyte aggregation by capillary microscopy. Using laser Doppler anemometry, we were able to show that this increase was predominantly located in the superficial layer capillaries (Δ44.53 ± 135.81%, n.s.) and less so in deeper layer arterioles (Δ2.75 ± 24.84%, n.s.). Vascular response to heat and cryo stress was also improved after LA but failed to reach significance. LA significantly reduced levels of epinephrin (-33 ± 39.2%), ANP (-28.8 ± 20.2%), ADMA (-74.1 ± 23%), and fibrinogen (-45.4 ± 19.7%) when comparing before LA and after LA values. In summary, we found an improvement in the microcirculation of the upper limbs under LA, which may result from a decrease of vasoconstrictors, improvement of vasomotor function, and a decrease in blood viscosity or erythrocyte aggregation.

Topics: Adult; Aged; Arginine; Atrial Natriuretic Factor; Blood Component Removal; Blood Flow Velocity; Endothelin-1; Epinephrine; Erythrocyte Aggregation; Female; Fibrinogen; Hand; Humans; Hypercholesterolemia; Hyperlipoproteinemia Type II; Laser-Doppler Flowmetry; Lipids; Male; Microcirculation; Microscopic Angioscopy; Middle Aged; Norepinephrine; Photoplethysmography

Clinical efficacy of cardiac cell therapy may be compromised by its target population, patients with endothelial dysfunction. In vivo inhibition by endothelial dysfunction has been demonstrated for protein angiogenesis but remains unclear for cell therapy. We examined whether hypercholesterolemia inhibits vasculogenic effects of transplanted human circulating progenitor cells in ischemic tissue and whether L-arginine, a nitric oxide donor, might prevent impairment.. Athymic rats were fed either normal (group A) or high-cholesterol diets, the latter without (group B) or with (group C) oral L-arginine supplementation. Two weeks later, these rats underwent left femoral artery ligation followed by injection of 2 x 10(6) human circulating progenitor cells into left hind-limb muscle. A fourth group (group D) received supplemented high-cholesterol diets but no cells.. Group B had biochemical evidence of endothelial dysfunction and reduced tissue endothelial nitric oxide synthase expression, whereas group A levels were the same as in group C. By 21 postoperative days, left hind-limb perfusion had recovered fully in groups A and C, partially in D, and not at all in B (38% lower than group A, P < or = .004). Lower arteriolar densities were found in groups and B and D than in groups A and C (P < or = .02). Engrafted human cell numbers were equivalent in all cell-transplanted groups after 3 weeks.. Endothelial dysfunction inhibited effects of cell therapy, specifically vasculogenesis, suggesting a role for substrate modification to overcome this inhibition. Involved mechanisms appear related to use of cells but not engraftment and require further investigation.

Topics: Animals; Arginine; Cytokines; Endothelial Cells; Endothelin-1; Extremities; Humans; Hypercholesterolemia; Neovascularization, Physiologic; Nitrites; Rats; Rats, Nude; Rats, Sprague-Dawley

Hypercholesterolemia is associated with decreased nitric oxide (NO) bioavailability and endothelial dysfunction, a phenomenon thought to have a major role in the altered cerebral blood flow evident in stroke. Therefore, strategies that increase endothelial NO production have potential utility. Vascular reactivity of the middle cerebral artery (MCA) from C57BL/6J wild-type (WT) mice, apolipoprotein-E knockout (ApoE(-/-)) mice, and mice treated with the phosphodiesterase inhibitor cilostazol (100 mg/kg) was analyzed using the tension myograph. Contractile responses to endothelin-1 were significantly enhanced in MCA from ApoE(-/-) mice compared with WT mice (P<0.01), an effect absent in cilostazol-treated ApoE(-/-) mice. Acetylcholine-induced relaxation (which is entirely NO-dependent) was significantly impaired in MCA of ApoE(-/-) mice compared with WT mice (P<0.05), again an effect prevented by cilostazol treatment. Endothelial NOS phosphorylation at Ser(1179) was decreased in the aorta of ApoE(-/-) mice compared with WT mice (P<0.05), an effect normalized by cilostazol. Taken together, our data suggest that the endothelial dysfunction observed in MCA associated with hypercholesterolemia is prevented by cilostazol, an effect likely due to the increase in eNOS phosphorylation and, therefore, activity.

Topics: Animals; Aorta; Apolipoproteins E; Cells, Cultured; Cilostazol; Cyclic GMP; Endothelin-1; Endothelium, Vascular; Humans; Hypercholesterolemia; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Middle Cerebral Artery; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitrites; Phosphodiesterase Inhibitors; Tetrazoles; Vasoconstriction; Vasodilation

Simvaglyzin, a complex compound of simvastatin and glycyrrhizic acid, administered to rabbits with experimental hypercholesterolemiain in doses equivalent to 66.6 and 40 microg/kg simvastatin exhibited antioxidant capacity (decreased the content of lipid peroxidation products in the blood by 27-41%) and endothelium-normalizing effect (decreased the level of von Willebrand factor and endothelin-1 by 26-58 and 21-29%, respectively, compared to 200 microg/kg simvastatin, p<0.05).

Topics: Analysis of Variance; Animals; Anticholesteremic Agents; Antioxidants; Aryldialkylphosphatase; Cholesterol; Diet; Endothelin-1; Endothelium, Vascular; Fluorometry; Glycyrrhizic Acid; Hypercholesterolemia; Male; Nitrous Oxide; Rabbits; Simvastatin; von Willebrand Factor

Potassium channels in vascular smooth muscle (VSM) control vasodilation and are potential regulatory targets. This study evaluated effects of sex differences, exercise training (EX), and high-fat diet (HF) on K(+) currents (I(K)) of coronary VSM cells. Yucatan male and female swine were assigned to either sedentary confinement (SED), 16 wk of EX, 20 wk of HF, or 20 wk of HF with 16 wk of EX (HF-EX). VSM cells of normal-diet SED animals exhibited three components of I(K): 4-aminopyridine-sensitive I(K(KV)), TEA-sensitive I(K(BK)), and 4-aminopyridine + TEA-insensitive I(K). Females exhibited significantly higher basal I(K) than males in the same group. EX increased basal I(K) in males and females. HF reduced I(K) in males and females and nullified effects of EX. Endothelin-1 increased I(K) significantly in males but not in females. In the presence of endothelin-1, 1) I(K(KV)) was similar in SED males and females and EX increased I(K(KV)) to a greater extent in males than in females and 2) I(K(BK)) was greater in SED females than in males and EX increased I(K(BK)) to a greater extent in males, resulting in I(K(BK)) similar to EX females. Importantly, HF nullified effects of EX on I(K(KV)) and I(K(BK)). These data indicate that basal I(K) of SED female swine is inherently greater than that shown in SED males and that males require EX to achieve comparable levels of I(K). Importantly, HF reduced I(K) in males and females and nullified effects of EX, suggesting HF abrogates beneficial effects of EX on coronary smooth muscle.

Topics: Animals; Coronary Vessels; Dietary Fats; Disease Models, Animal; Endothelin-1; Female; Hypercholesterolemia; Male; Membrane Potentials; Muscle Contraction; Muscle, Smooth, Vascular; Physical Conditioning, Animal; Potassium; Potassium Channels, Voltage-Gated; Random Allocation; Sex Characteristics; Swine; Swine, Miniature

Epidemiological studies showed that hypercholesterolemia is associated with higher left ventricular mass. Endothelin signaling is activated in hyperlipidemic animals and may contribute to progressive ventricular hypertrophy. Simvastatin has been shown to inhibit endothelin-1. However, the behavior of simvastatin on ventricular hypertrophy in hyperlipidemic animals is not well understood. In this study, we evaluated the hemodynamic, biochemical, and morphological responses to simvastatin in cholesterol-fed (1%) rabbits. The left ventricular weight increased 8 wk after cholesterol feeding compared with that in normocholesterolemic rabbits. Simvastatin at a clinical therapeutic dose (1.2 mg x kg(-1) x day(-1)) significantly decreased left ventricular weight by 14% and left ventricular myocyte sizes by 14% as isolated by enzymatic dissociation. Hypercholesterolemia upregulated ventricular preproendothelin-1 mRNA as assessed by real-time quantitative RT-PCR and elevated production of cardiac endothelin-1 concentration. The increased endothelin-1 responses can be inhibited after simvastatin administration. Left ventricular mass indexed by body weight positively correlated with tissue endothelin-1 levels (P = 0.0003). In Langendorff-perfused rabbit hearts, hyperlipidemia led to significant QT prolongation compared with normocholesterolemia, which can be reversed by administering simvastatin. In contrast, simvastatin-induced beneficial effects were reversed by the addition of mevalonate. The addition of bosentan, a nonspecific endothelin receptor blocker, improved the response in hypercholesterolemic rabbits and did not have additional beneficial effects in simvastatin-treated rabbits. The results of the present study suggest that the antihypertropic and electrocardiographic effects of simvastatin at a clinical therapeutic dose are mediated through inhibition of tissue endothelin-1 expression, which is linked to mevalonate metabolism, and result in an amelioration of cardiomyocyte hypertrophy development by an atherogenic diet.

Topics: Animals; Cholesterol; Electrocardiography; Endothelin-1; Hypercholesterolemia; Hypertrophy, Left Ventricular; Hypolipidemic Agents; Linear Models; Long QT Syndrome; Male; Myocytes, Cardiac; Perfusion; Rabbits; RNA, Messenger; Simvastatin

The novel vaso-constricting 31-amino acid-length endothelin-1 [ET-1(1-31)] is selectively produced by human mast cell chymase via its action on big ET-1. However, the pathological role of ET-1(1-31) in atherosclerosis remains unclear. The aim of this study was to clarify vasoconstrictive response and expression of ET-1(1-31) in atherosclerotic aorta.. Syrian golden hamster, was used for preparing the atherosclerotic models by the administration of a high cholesterol diet (HC), treatment with the nitric oxide synthase inhibitor (Nomega-nitro-L-arginine methylester, L-NAME) alone, or both (HC and L-NAME) for 40 weeks. Early atherosclerosis was observed in the case of HC or L-NAME alone treatments respectively and severe atherosclerosis was observed in the case of combined HC and L-NAME treatment. Vasoconstriction induced by ET-1(1-31) was not altered by the atherosclerotic changes, but the expression pattern of ET-1(1-31) was different at each stage of the atherosclerotic aorta. ET-1(1-31) was observed rarely in normal aortas or in early atherosclerotic lesions, but ET-1(1-31) expression was dramatically increased in aortic neointima and adventitia in a state of atherosclerosis with severe inflammation.. ET-1(1-31) might play in a role of promoting atherosclerosis, and especially be involved in inflammatory mediation during the progression of atherosclerosis.

Topics: Animals; Aorta, Thoracic; Arteriosclerosis; Blood Pressure; Cholesterol; Cricetinae; Disease Models, Animal; Endothelin-1; Heart Rate; Hypercholesterolemia; Male; Peptide Fragments; Triglycerides; Vasoconstriction

The effect of red wine and wine polyphenol resveratrol on endothelial function was investigated in experimental hypercholesterolemic rabbits. Endothelial function as measured by flow-mediated dilation (FMD) in the femoral artery was 19.28+/-2.81% in control animals fed a regular diet. In contrast, rabbits fed a high-cholesterol (1.5%) diet showed a reduced endothelial function, as revealed by a 25% reduction in the measured FMD. Intragastric feeding of resveratrol (3 mg/kg/day), red wine (4 ml/kg/day), dealcoholized red wine (4 ml/kg/day), for 12 weeks in hypercholesterolemic rabbits significantly mitigated the reduction in endothelial function, and resulted in FMD values of 14.52+/-0.60, 18.95+/-2.30, 17.58+/-1.43, and 18.80+/-3.94%, respectively. Measurement of plasma endothelin 1 (ET-1) and nitric oxide (NO) levels showed that feeding a high-cholesterol diet significantly increased plasma ET-1 levels (from 51.4+/-17.6 to 96.9+/-24.3 pg/ml), and decreased plasma NO concentration (from 104.6+/-18.5 to 67.7+/-16.1 pg/ml). With administration of resveratrol, red wine, or dealcoholized red wine, plasma ET-1 levels statistically decreased, in parallel with a significant elevation in NO levels. These results provide in vivo evidence suggesting that resveratrol and red wine improve endothelial function, which may be one of the mechanisms by which this red wine polyphenol exerts its alcohol-independent cardioprotective effects.

Topics: Administration, Oral; Animals; Endothelin-1; Endothelium, Vascular; Hypercholesterolemia; Hypolipidemic Agents; Male; Nitric Oxide; Phenols; Rabbits; Resveratrol; Stilbenes; Vasodilation; Wine

Coronary endothelial dysfunction is associated with an increase in cardiac events. Hypercholesterolemia (HC) and hypertension (HT) are both associated with endothelial dysfunction, and their coexistence is associated with an increased incidence of cardiac events in epidemiological studies. However, pathogenic mechanisms are poorly understood. Here we studied the effects of coexisting HC and HT on coronary endothelial function.. Four groups of pigs were studied after 12 weeks of a normal diet (n=9), a 2% HC diet (n=9), HT (achieved by unilateral renal artery stenosis, n=8), or HC+HT (n=6). Coronary endothelial function was tested, in epicardial arteries and arterioles, by using organ chamber techniques. Oxidative stress was measured in coronary artery tissue. Vasodilatory response to bradykinin and calcium ionophore was significantly impaired in animals with HC+HT compared with each risk factor alone (P<0.05 for both). In animals with coexistent HC and HT, the increase in oxidative stress was more pronounced compared with each risk factor alone (P<0.05). Furthermore, chronic antioxidant supplementation significantly improved coronary artery vasoreactivity.. These results suggest that HC and HT have a synergistic deleterious effect on coronary endothelial function, associated with increased oxidative stress. This interaction may contribute to the increased incidence of coronary heart disease and cardiac events seen when HC and HT coexist.

Topics: Animals; Antioxidants; Ascorbic Acid; Bradykinin; Calcimycin; Coronary Artery Disease; Coronary Vessels; Cyclic GMP; Diet, Atherogenic; Endothelin-1; Endothelium, Vascular; Female; Hemodynamics; Hypercholesterolemia; Hypertension, Renovascular; Lipids; Nitric Oxide; Nitroprusside; Oxidative Stress; Renal Artery Obstruction; Renin; Substance P; Swine; Vasodilator Agents; Vitamin E

Endothelin-1 (ET-1) is a potent vasoconstrictor that increases vascular tone in the resistance vessels of subjects with hypertension. It is unclear whether endogenous ET-1 affects resistance-vessel function equally in patients with other cardiovascular risk factors. Vasoconstriction to ET-1 is mediated principally via the endothelin-A (ETA) receptor on vascular smooth muscle cells. Accordingly, we used an ETA-specific antagonist, BQ-123, to test the hypothesis that endogenous ET-1 increases vascular resistance selectively in subjects with hypertension compared with other risk factors. BQ-123 was infused at 100 nmol/min for 80 minutes into the brachial artery of 10 subjects with hypertension (mean+/-SEM arterial pressure, 106+/-5 mm Hg), 12 subjects with hypercholesterolemia (mean+/-SEM total cholesterol, 7.1+/-0.2 mmol/L), 10 active smokers (mean+/-SEM, 42+/-11 pack-years), and 11 healthy, age-matched individuals. Forearm blood flow (FBF) was measured by venous occlusion plethysmography. BQ-123 dilated resistance arterioles in hypertensive subjects, with FBF's increasing by 46+/-7% from baseline (P<0.001). BQ-123 increased FBF to a lesser extent in hypercholesterolemic (24+/-5%, P<0.001) and healthy (20+/-8%, P=0.007) individuals but did not affect FBF significantly in smokers (10+/-8%, P=0.185). The vasodilator response in hypertensive subjects, but not in hypercholesterolemic patients or smokers, was significantly greater than that in healthy individuals (P=0.012). Endogenous ET-1, acting via the ETA receptor, increases resistance-vessel tone in subjects with hypertension more than in subjects with hypercholesterolemia or in smokers. These results indicate that ET-1 contributes more to the pathophysiology of hypertension than of other risk factors in subjects without overt atherosclerosis.

Topics: Arteriosclerosis; Endothelin Receptor Antagonists; Endothelin-1; Female; Forearm; Humans; Hypercholesterolemia; Hypertension; Male; Middle Aged; Peptides, Cyclic; Receptor, Endothelin A; Regional Blood Flow; Risk Factors; Smoking; Vascular Resistance; Vasodilation

We sought to demonstrate, in an appropriate animal model, that co-medication with a transcription factor-blocking agent limits restenosis after percutaneous transluminal coronary angioplasty (PTCA).. Enhanced synthesis in the vessel wall of endothelin-1 (ET-1), a powerful co-mitogen for vascular smooth muscle cells, appears to be one mechanism that promotes restenosis after PTCA. Deformation-induced expression of prepro-ET-1 is governed by the transcription factor, activator protein-1 (AP-1).. An anti-AP-1 decoy oligodeoxynucleotide (dODN) strategy was devised in which the dODN-containing solution (20 nmol) was administered locally through a Dispatch catheter into the coronary arteries of hypercholesterolemic minipigs at the time of PTCA (AVE-GFX stent).. Treatment with an AP-1 dODN, mimicking the consensus binding site of the transcription factor, significantly reduced neointimal formation in the coronary arteries of hypercholesterolemic minipigs (n = 10 to 12), compared with vehicle-treated coronary arteries, after four weeks of follow-up (neointimal area 2.64 +/- 0.33 vs. 4.81 +/- 1.04 mm(2) [mean +/- SEM]; p < 0.05). This effect was maintained after eight weeks (neointimal area 2.04 +/- 0.22 mm(2); n = 3) and correlated with a reduction in both nuclear translocation of AP-1 and ET-1 synthesis in the vessel wall 48 h after PTCA (n = 4). In contrast, an AP-1 mutant dODN, to which the transcription factor does not bind, showed no effect on neointimal formation at either time point (n = 3 to 7). Moreover, a consensus dODN directed against CCAAT/enhancer binding protein (C/EBP), another deformation-sensitive transcription factor, did not significantly affect neointimal formation after four weeks (n = 3).. These findings demonstrate the feasibility, efficacy and specificity of the anti-AP-1 dODN approach to the treatment of restenosis, which principally but not exclusively targets deformation-induced ET-1 synthesis in the vessel wall. Provided that these findings can be extrapolated to the situation of patients with coronary artery disease, the observed extent of the inhibitory effect of the AP-1 dODN treatment suggests that this co-medication may greatly reduce the incidence of in-stent restenosis.

Topics: Angioplasty, Balloon, Coronary; Animals; Cardiac Catheterization; Coronary Artery Disease; Coronary Restenosis; Coronary Vessels; Disease Models, Animal; Endothelin-1; Feasibility Studies; Hypercholesterolemia; Oligonucleotides; Swine, Miniature; Transcription Factor AP-1; Transcription Factors; Tunica Intima

This study investigates the plasma activity of inflammatory mediators such as granulocyte-macrophage colony-stimulating factor (GM-CSF), C-C chemokines and soluble adhesion molecules, produced by monocyte-endothelial cell adhesive interaction, in patients with arterial hypertension.. We studied 66 untreated patients with mild to moderate arterial hypertension (hypercholesterolemic: 34, normocholesterolemic: 32) and 30 sex- and age-matched normocholesterolemic normotensive controls. Plasma concentrations of GM-CSF, macrophage chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1alpha (MIP-1alpha), RANTES (regulated on activation normally T-cell expressed and secreted), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1), as well as plasma endothelin-1 (ET-1), were determined in study population by ELISA and RIA, respectively.. Hypertensives exhibited significantly higher levels of GM-CSF (6.5+/-1.3 vs. 2.3+/-0.7 pg/ml, P=0.099), MCP-1 (175+/-31 vs. 120+/-24 pg/ml, P=0.0093), MIP-1alpha (23+/-4 vs. 15+/-2 pg/ml, P=0.0089), RANTES (17+/-4 vs. 14+/-3 ng/ml, P=0.047), sICAM-1 (235+/-39 vs. 187+/-21 ng/ml, P=0.0041), sVCAM-1 (684+/-42 vs. 589+/-23 ng/ml, P=0.0045) and ET-1 (6.1+/-1.5 vs. 2.4+/-0.3 pg/ml, P=0.0095) than those of normotensives. The normocholesterolemic hypertensives had significantly lower levels of GM-CSF, MCP-1, MIP-1alpha, sICAM-1 and sVCAM-1 than hypercholesterolemic hypertensives but higher than normotensives. In hypertensives, ET-1 levels were significantly correlated with mean arterial pressure (r=0.51, P=0.028), MCP-1 values (r=0.45, P=0.047) and sICAM-1 levels (r=0.64, P=0.0090). Significant correlations were also found between LDL cholesterol values and plasma inflammatory factors GM-CSF (r=0.58, P=0.0088), MCP-1 (r=0.49, P=0.040) and sICAM-1 (r=0.53, P=0.034) in the hypercholesterolemic sub-group of hypertensives.. Inflammatory markers of monocyte-endothelial cell adhesive interaction are elevated in hypertensives in comparison to normotensives and may be related to plasma ET-1 activity. The coexistence of hypercholesterolemia may enhance this inflammatory process induced by arterial hypertension.

Topics: Biomarkers; Blood Pressure; Body Mass Index; Chemokine CCL2; Chemokine CCL3; Chemokine CCL4; Chemokine CCL5; Endothelin-1; Female; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Hypercholesterolemia; Hypertension; Inflammation Mediators; Intercellular Adhesion Molecule-1; Macrophage Inflammatory Proteins; Male; Middle Aged; Smoking; Statistics as Topic; Vascular Cell Adhesion Molecule-1

The purpose of this study was to test the hypothesis that endothelin (ET) receptor antagonism reduces coronary vasa vasorum neovascularization in experimental hypercholesterolemia.. Experimental hypercholesterolemia is associated with increased expression of ET-1, an endothelium-derived peptide with vasoconstricting, mitogenic and angiogenic properties, in the coronary arterial wall as well as with vasa vasorum neovascularization. A pathomechanistic role of the endogenous ET system in vasa vasorum neovascularization in hypercholesterolemia has, however, remained uncertain so far.. Female domestic pigs were placed on a normal diet (N; n = 7) or on a hypercholesterolemic diet without (HC; n = 6) or with ET-A receptor antagonism (ABT-627, 4 mg/kg/day; HC + ET-A; n = 6). After 12 weeks, coronary vasa vasorum structure was assessed by three-dimensional microscopic computed tomography, expression of vascular endothelial growth factor (VEGF) within the coronary arterial wall by Western blotting and immunostaining.. Compared with the N group, plasma concentrations of low-density lipoprotein cholesterol were higher in both the HC and HC + ET-A groups (36 +/- 3 mg/dl vs. 312 +/- 153 mg/dl and 303 +/- 113 mg/dl, p < 0.01). Vasa vasorum density was higher in the HC group compared with the N group (4.7 +/- 1.8 per mm(2) vs. 2.5 +/- 1.5 per mm(2); p < 0.05) and was preserved in the HC + ET-A group (3.2 +/- 0.7 per mm(2)). In parallel, increase in VEGF expression in the coronary arterial wall in the HC group was preserved in the HC + ET-A group.. The current study demonstrates that chronic endothelin receptor antagonism prevents the increase in VEGF expression and vasa vasorum density of coronary arteries in experimental hypercholesterolemia. These findings support a role for the endogenous ET system in vasa vasorum neovascularization in early coronary atherosclerosis.

Topics: Animals; Blotting, Western; Cholesterol, Dietary; Coronary Artery Disease; Coronary Vessels; Disease Models, Animal; Endothelial Growth Factors; Endothelin Receptor Antagonists; Endothelin-1; Female; Hypercholesterolemia; Immunohistochemistry; Lymphokines; Neovascularization, Pathologic; Swine; Tomography, X-Ray Computed; Vasa Vasorum; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

Many cytokine genes, including those encoding acute-phase proteins and immunoglobulins, share binding sites for the CCAAT/enhancer-binding protein (C/EBP) in their 5'-flanking regions, and C/EBP-related transcription factors regulate cell proliferation during terminal differentiation. Therefore, C/EBP represents an attractive target for inhibiting restenosis after balloon angioplasty. In a rabbit model of restenosis that combines balloon injury of the carotid artery with cholesterol-mediated chronic inflammation, a decoy oligodeoxynucleotide (ODN) capable of neutralizing C/EBP was administered to the site of injury for 30 minutes. Electrophoretic mobility shift analysis confirmed that C/EBP activity in decoy ODN-treated segments was virtually absent after 2 days. Morphometric analysis after 28 days revealed significant reduction (up to 50%) of neointimal formation and intravascular inflammation in decoy ODN-treated segments compared with mutant control ODN or vehicle-treated segments. In addition, de novo synthesis of endothelin-1 and the number of proliferating cell nuclear antigen-positive smooth muscle cells in the vessel wall were markedly attenuated at day 3. These findings suggest that decoy ODN-based neutralization of C/EBP may be a feasible and effective method to limit restenosis after angioplasty brought about, at least in part, by inhibiting the de novo synthesis of endothelin-1.

Topics: Animals; Arteriosclerosis; Catheterization; CCAAT-Enhancer-Binding Proteins; Disease Models, Animal; Endothelin-1; Hypercholesterolemia; Immunohistochemistry; Macrophages; Male; Oligodeoxyribonucleotides; Rabbits; Recurrence; Treatment Outcome; Tunica Intima

Endothelin (ET)-1 has proatherogenic properties, since ET receptor antagonists reduce atherosclerotic lesions in animals. However, we recently demonstrated that ET-1 and ET(B) receptors are increased in atherosclerotic lesions. To further examine the effects of ET(B) receptor antagonism on atherogenesis, we investigated the chronic effects of the nonselective ET(A)/ET(B) receptor antagonist SB209670 on the development of atherosclerosis in apolipoprotein E (ApoE)-deficient mice.. Ninety-four male mice (10 weeks of age) were randomly divided into four groups: mice fed a Western-type diet or a chow diet with SB209670 treatment (10 mg/kg/day) or placebo for 12 weeks.. In mice fed the Western-type diet, but not in mice fed the chow diet, treatment with SB209670 significantly attenuated the increase in plasma total cholesterol, predominantly in the very-low-density lipoprotein and intermediate-density lipoprotein fractions, without altering the plasma triglyceride level. Furthermore, treatment with SB209670 significantly reduced the extent of aortic atherosclerosis, by 53% in mice fed the Western-type diet and by 38% in mice fed the chow diet. Histological analysis revealed that SB209670 prevented the formation of atheromatous plaque lesions by inhibiting the fibroproliferative process.. We found that chronic administration of SB209670 reduced diet-induced hypercholesterolemia and atherosclerosis in ApoE-deficient mice. Thus, nonselective ET receptor antagonists may have a therapeutic potential in the treatment of human atherosclerotic disease.

Topics: Animals; Aorta; Apolipoproteins E; Arteriosclerosis; Blood Pressure; Cholesterol, Dietary; Cholesterol, VLDL; Diet; Disease Models, Animal; Endothelin Receptor Antagonists; Endothelin-1; Hypercholesterolemia; Indans; Lipoproteins; Male; Mice; Triglycerides

Topics: Animals; Biopterins; Cholesterol; Coronary Disease; Coronary Vessels; Dose-Response Relationship, Drug; Endothelin-1; Hypercholesterolemia; Superoxides; Swine

Topics: Animals; Diabetes Mellitus, Experimental; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Hypercholesterolemia; Hypertension; Kidney; Nitric Oxide; Nitric Oxide Synthase; Peptide Fragments; Rats; Rats, Inbred Dahl; Rats, Inbred SHR; Rats, Inbred WKY; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Vascular Resistance

Hypercholesterolemia (HC) is associated with coronary endothelial dysfunction and increased circulating levels of endothelin-1. We show that pre-treatment of intact rat aortic rings with cholesterol synergistically enhances the vasoconstriction induced by endothelin-1 suggesting that elevated levels of cholesterol may predispose to hypertension by modulating the vascular reactivity to endogenous vasoconstrictors. Moreover, we report that SB202190, a selective inhibitor of p38 MAPK, and PD98059 an inhibitor of MEK1/2 are able to abolish the vasoactive properties of cholesterol. MK-886, an inhibitor of 5-lipoxygenase is inefficient at blocking the vasoactive properties of cholesterol whereas NS-398, a selective inhibitor of cyclooxygenase-2 (COX-2) completely abolishes cholesterol-induced vasoconstriction. In intact rat aortae, cholesterol stimulates prostaglandin E(2) and prostaglandin F(2 alpha) production, an effect that can be completely prevented by inhibiting p38 MAPK, or COX-2. In vitro, cholesterol appears to stimulate a similar pro-inflammatory pathway in human cerebrovascular smooth muscle cells. Disruption of the MAPK/COX-2 pathway may represent a valuable therapy to block the hypertension associated with HC, as well as the development of atherosclerosis.

Topics: Animals; Cells, Cultured; Cerebrovascular Circulation; Cholesterol; Cyclooxygenase 2; Dinoprost; Dinoprostone; Drug Synergism; Endothelin-1; Humans; Hypercholesterolemia; In Vitro Techniques; Inflammation; Isoenzymes; Lipoxygenase Inhibitors; Male; Membrane Proteins; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases; Muscle, Smooth, Vascular; p38 Mitogen-Activated Protein Kinases; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Sprague-Dawley; Signal Transduction; Vasoconstriction

Endothelial markers endothelin 1 (ET-1) and von Willebrand factor (vWF) were assessed in patients with type 2 diabetes and dyslipidemia and in patients with hypercholesterolemia.. In this case-control study, plasma ET-and vWF levels were measured by enzyme-linked immunosorbent assay in 35 normoalbuminuric type 2 diabetic patients with dyslipidemia (56+/-5 years), in 21 nondiabetic patients with hypercholesterolemia (52+/-7 years), and in 19 healthy control subjects (45+/-4 years). All of the individuals were normotensive and nonsmokers. Urinary albumin was measured by immunoturbidimetry.. ET-1 levels were higher (P<0.0001) in type 2 diabetic dyslipidemic patients (1.62+/-0.73 pg/ml) than in both nondiabetic hypercholesterolemic patients (0.91+/-0.73 pg/ml) and control subjects (0.69+/-0.25 pg/ml). vWF levels were significantly increased (P = 0.02) in type 2 diabetic (185.49+/-72.1%) and hypercholesterolemic (163.29+/-50.7%) patients compared with control subjects (129.70+/-35.2%). In the multiple linear regression analysis. ET-1 was significantly associated (adjusted r2 = 0.42) with serum triglyceride levels (P<0.001), age (P<0.01), insulin sensitivity index (P<0.02), and albuminuria levels (P<0.04). vWF levels were associated (adjusted r2 = 0.22) with albuminuria (P<0.001), fibrinogen levels (P<0.02), and BMI (P<0.03).. Compared with hypercholesterolemic patients, type 2 diabetic patients with dyslipidemia have increased levels of ET-1 and vWF which may indicate more pronounced endothelial injury. These findings appear to be related to components of the insulin resistance syndrome.

Topics: Albuminuria; Blood Pressure; Case-Control Studies; Diabetes Mellitus, Type 2; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Female; Humans; Hypercholesterolemia; Hyperlipidemias; Lipoproteins; Male; Middle Aged; Reference Values; Triglycerides; von Willebrand Factor

Although endothelin-1 (ET-1) is involved in balloon-induced neointima formation, the role of ET-1 in balloon-induced neointima formation in hypercholesterolemia is unclear. In addition, it remains to be determined whether ET-1 is produced by endothelial cells or vascular smooth muscle cells, or both. We investigated tissue immunoreactive ET-1 levels by immunoblot analysis, localization of ET-1 immunoreactivity by immunohistochemistry, and expression of preproET-1 mRNA by in situ hybridization in balloon-induced neointima formation in experimental hypercholesterolemic rats. Serum total cholesterol levels were significantly higher (p< 0.01) in the 5%cholesterol-diet group (194 +/- 17 mg/dl, n=20) than in the normal-diet group (64 +/- 2 mg/dl, n=20). Before and after endothelial denudation, plasma ET-1 levels and tissue immunoreactive ET-1 levels were significantly higher in cholesterol-diet rats. The expression of preproET-1 mRNA by in situ hybridization was observed in the nuclei of endothelial cells, but not medial smooth muscle cells in normal- or cholesterol diet rats. After endothelial denudation, plasma ET-1 levels and serum total cholesterol levels did not change in either the normal- or the cholesterol-diet rats. Tissue level of ET-1 tended to increase at 3 days after denudation in normal-diet rats (1.0 +/- 0.1 vs 2.6 +/- 0. 2 density ratio, p< 0.05), although endothelial cells had not yet regenerated. The expression of preproET-1 mRNA by in situ hybridization was not observed at 3 days after endothelial denudation in either endothelial or medial smooth muscle cells in normal-diet rats. Four weeks after denudation, regeneration of endothelial cells was almost complete, and an intimal hyperplasia was observed. Tissue ET-1 levels were significantly elevated 4 weeks after endothelial denudation in normal-diet rats (1.0 +/- 0.1 vs 7.6 +/- 0.2 density ratio, p< 0.05). The expression of preproET-1 mRNA by in situ hybridization was observed in the nuclei of regenerated endothelial cells after endothelial denudation, and in smooth muscle cells migrating into the intima, but was not observed in medial smooth muscle cells in normal-diet rats. A similar pattern was observed in cholesterol-diet rats. We concluded that ET-1 was involved in neointima formation and that ET-1 was produced by both endothelial and neointimal smooth muscle cells, but not medial smooth muscle cells after endothelial denudation in experimental hypercholesterolemic rats.

Topics: Angioplasty, Balloon, Coronary; Animals; Aorta, Thoracic; Catheterization; Endothelin-1; Endothelium, Vascular; Hypercholesterolemia; Male; Muscle, Smooth, Vascular; Rats; Rats, Wistar

We sought to assess the activity of endogenous endothelin-1 (ET-1) in hypercholesterolemic patients using antagonists of ET-1 receptors.. Endothelial dysfunction in hypercholesterolemic patients may contribute to their risk of premature atherosclerosis. Endothelin, a peptide released by endothelial cells, may be involved in this process by activating smooth muscle cell mitogenesis and leukocyte adhesion.. Forearm blood flow (FBF) responses (strain-gauge plethysmography) to intra-arterial infusion of a selective blocker of ETA receptors (BQ-123) and, on a separate occasion, to ET-1 were measured in 12 hypercholesterolemic patients and 12 normal control subjects. In addition, on a different day, six hypercholesterolemic patients received co-infusion of BQ- 123 and BQ-788 (a selective blocker of ETB receptors).. In normal subjects, BQ-123 did not significantly modify FBF from baseline (p = 0.78); however, in hypercholesterolemic patients, BQ-123 administration resulted in a significant vasodilator response (p < 0.001). Administration of exogenous ET-1 resulted in similar vasoconstrictor responses in patients (37%) and control subjects (35%) (p = 0.83). In hypercholesterolemic patients, the vasodilator response to selective ETA blockade was reversed by nonselective blockade of ET-1 receptors obtained by co-infusion of BQ-123 and BQ-788.. The vascular activity of endogenous ET-1 is enhanced in hypercholesterolemic patients, whereas their sensitivity to exogenous ET-1 is unchanged. These findings suggest increased production of ET-1, which may participate in the pathophysiology of vascular disease characteristic of hypercholesterolemia.

Topics: Endothelin Receptor Antagonists; Endothelin-1; Female; Humans; Hypercholesterolemia; Male; Middle Aged; Receptor, Endothelin A; Receptor, Endothelin B; Regional Blood Flow

Although endothelin-1 is a potent vasoconstrictor peptide, stimulation of endothelin type B receptor (ETBR) causes bidirectional changes in vascular tone, ie, vasodilation and vasoconstriction. Roles of ETBR in pathological conditions are largely unknown.. We studied the effect of BQ-3020, a highly selective ETBR agonist, on renal vascular resistance and nitric oxide (NO) release in the isolated, perfused kidney of rats with hypertension, diabetes mellitus, and hypercholesterolemia. Immunohistochemistry of endothelial NO synthase and ETBR was also examined. Infusion of BQ-3020 at concentrations of

Topics: Animals; Blood Pressure; Diabetes Mellitus, Experimental; Endothelin-1; Endothelins; Hypercholesterolemia; Hypertension; Immunohistochemistry; In Vitro Techniques; Kidney; Male; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Peptide Fragments; Rats; Rats, Inbred Dahl; Rats, Inbred SHR; Rats, Inbred WKY; Rats, Sprague-Dawley; Receptor, Endothelin B; Receptors, Endothelin; Vascular Resistance

Lipid-lowering statin treatment reduces cardiovascular morbidity and mortality and improves endothelial function in patients with hypercholesterolemia. The aim of the present study was to evaluate plasma levels of fibrinogen, factor VII, and the macrophage-derived inflammatory mediator neopterin during lipid lowering. In addition, the endothelial production of platelet antiaggregatory and vasodilatory factors such as nitric oxide and prostacyclin, and vasoconstrictive factors such as endothelin-1, was assessed. Plasma fibrinogen, factor VII, endothelin-1, and the neopterin and intraplatelet nitric oxide and prostacyclin mediators cyclic 3'-5'guanosine monophosphate (cGMP) and cyclic 3'-5'adenosine monophosphate (cAMP) were measured before and 6 months after the institution of treatment with fluvastatin in 17 patients (eight men and nine women, median age 60 years) with vascular disease and previously untreated hypercholesterolemia. After 6 months, a decrease of 1.62 mmol/l [1.26-2.18 (19%); P < 0.01] was noted in levels of total cholesterol, and a decrease of 1.70 mmol/l [1.52-2.30 (28%); P < 0.01] in levels of low-density lipoprotein cholesterol. Plasma levels of fibrinogen had increased [from 4.81 g/l (4.26-5.27) to 5.17 g/l (4.81-5.67); P < 0.05], whereas no significant changes had occurred in intraplatelet levels of cGMP [decrease by 0.05 pmol/10(9) platelets (-0.17 to 0.24); NS], cAMP [decrease by 0.13 pmol/10(9) platelets (-0.37 to 0.86); NS], plasma endothelin-1 [decrease by 0.05 pg/ml (-0.60 to 0.70); NS], plasma factor VII [from 1.14 IE/ml (0.58-1.38) to 1.22 IE/ml (0.96-1.46); NS], or plasma neopterin [from 8.6 nmol/l (7.1-11.5) to 8.7 nmol/l (7.9-11.3); NS]. In conclusion, during cholesterol-lowering treatment with fluvastatin, plasma levels of fibrinogen increased whereas intraplatelet cyclic nucleotide levels and plasma endothelin-1, factor VII and neopterin levels were unchanged.

Topics: Aged; Anticholesteremic Agents; Blood Platelets; Cardiovascular Diseases; Cholesterol; Endothelin-1; Factor VII; Fatty Acids, Monounsaturated; Female; Fibrinogen; Fluvastatin; Humans; Hypercholesterolemia; Indoles; Male; Middle Aged; Neopterin; Nucleotides, Cyclic

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

Insulin and insulin-like growth factor (IGF) 1 affect coronary vasoactivity. Experimental hypercholesterolemia is associated with coronary atherogenesis and altered vasomotor regulation. Because the IGF axis is altered during atherogenesis, we postulated that experimental hypercholesterolemia is associated with an altered coronary vasoactive response to IGF-1 in vitro. Coronary arteries and arterioles from pigs fed either a normal or high-cholesterol diet for 10 weeks were contracted with endothelin-1 and relaxed with cumulative concentrations of insulin or IGF-1 (10(-12) to 10(-7) mol/L). Control arterioles were also incubated with the nitric oxide synthase inhibitor 10(-4) mol/L N(G)-monomethyl-L-arginine (L-NMMA) or the potassium channel blocker 10(-2) mol/L tetraethylammonium (TEA), contracted with endothelin-1, and relaxed with insulin or IGF-1. Experimental hypercholesterolemia (1) increased serum cholesterol (9.5+/-1.0 versus 1.9+/-0.08 mmol/L; P<0.0001), (2) caused coronary arterial and arteriolar endothelial dysfunction in vitro (attenuated vasorelaxation to bradykinin), (3) did not alter the epicardial response to either insulin (P=0.80) or IGF-1 (P=0.12), and (4) significantly attenuated the arteriolar response to IGF-1 (maximal relaxation of 79+/-6% versus 42+/-8%; P=0.01) but not insulin (43+/-6% versus 53+/-7%; P=0.99). Control arteriolar vasorelaxation to IGF-1 was attenuated by both L-NMMA (P<0.001) and TEA (P=0.01), whereas only L-NMMA attenuated insulin (P<0.001). Staining for IGF-1 and IGF binding protein 2 was increased (P<0.05) in arterioles of cholesterol-fed pigs. IGF-1 and insulin are therefore coronary arteriolar vasorelaxants through different mechanisms. Experimental hypercholesterolemia is associated with resistance to the coronary arteriolar vasorelaxing effects of IGF-1 but not insulin, in conjunction with increased ligand and binding-protein expression. The IGF axis may contribute to the altered coronary vasoactivity in hypercholesterolemia.

Topics: Animals; Arteries; Arterioles; Coronary Vessels; Endothelin-1; Endothelium, Vascular; Hypercholesterolemia; Immunologic Techniques; In Vitro Techniques; Insulin; Insulin-Like Growth Factor Binding Protein 2; Insulin-Like Growth Factor I; Nitric Oxide; Pericardium; Potassium Channels; Reference Values; Swine; Vasoconstriction; Vasodilation

Topics: Animals; Arteriosclerosis; Endothelin-1; Hypercholesterolemia; Muscle, Smooth, Vascular; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Rabbits

Endothelin (ET) may mediate the enhanced coronary vasoconstriction associated with hypercholesterolemia. We hypothesized that short-term inhibition of ET receptors attenuates the coronary epicardial vasoconstrictor response to acetylcholine in experimental hypercholesterolemia. ET-1 (group I, n=5; 5 ng x kg[-1] x min[-1]) and acetylcholine (group III, n=7; 10[-6] to 10[-4] mol/L) were given by intracoronary infusion in pigs. ET-1 and acetylcholine were also infused with the specific ETA-receptor blocker FR-139317 (5 microg x kg[-1] x min[-1]; group II, n=6; group IV, n=6). Acetylcholine was also infused with the combined ET-receptor blocker, bosentan (0.5 mg/kg plus 1 mg x kg[-1] x h[-1], group V, n=5). The ETB-receptor agonist sarafotoxin 6c (5 ng x kg[-1] x min[-1]; n=4) was also infused. The percentage change in coronary artery diameter (%deltaCAD) to the infusions was measured at baseline and after 10 weeks of high-cholesterol diet in all animals. Sarafotoxin 6c mildly reduced %deltaCAD at baseline and 10 weeks (-10+/-2% and -12+/-3%, respectively). FR-139317 did not attenuate the epicardial vasoconstrictor response to ET-1 at baseline (%deltaCAD -18+/-8% for group I versus -12+/-6% for group II; P=NS) but did at 10 weeks (%deltaCAD -77+/-14% for group I versus -14+/-6% for group II; P<.05). FR-139317 did not affect the response to acetylcholine at baseline (%deltaCAD 5+/-2% for group III versus 7+/-3% for group IV, P=NS) or at 10 weeks (%deltaCAD -23+/-12% for group III versus -19+/-7% for group IV; P=NS). Bosentan did not affect the response to acetylcholine at baseline or 10 weeks. Short-term ET-receptor inhibition in experimental hypercholesterolemia attenuated the enhanced coronary epicardial vasoconstrictor effects of ET-1 but not acetylcholine-induced coronary epicardial vasoconstriction, suggesting that acetylcholine-induced coronary epicardial vasoconstriction may not be mediated by ET receptors.

Topics: Acetylcholine; Animals; Antihypertensive Agents; Azepines; Blood Pressure; Bosentan; Cholesterol; Coronary Vessels; Diet, Atherogenic; Endothelin Receptor Antagonists; Endothelin-1; Hemodynamics; Hypercholesterolemia; Indoles; Receptors, Endothelin; Sulfonamides; Swine; Vasoconstriction; Vasoconstrictor Agents; Viper Venoms

The endothelium regulates vascular function by releasing the vasodilator autacoid nitric oxide (NO) and the vasoconstrictor peptide endothelin-1 (ET-1). Impaired activity of NO as well as excessive activity of ET-1 have been demonstrated in hypercholesterolemia and atherosclerosis. Because dietary L-arginine can restore NO function and improve abnormal endothelium-dependent relaxation in hypercholesterolemic rabbits, we examined the effects of dietary supplementation with L-arginine in cholesterol-fed rabbits on endothelium-dependent vascular relaxation and ET-1-induced vascular contraction, as well as the systemic synthesis of ET-1. Rabbits were initially fed a diet enriched with 1% cholesterol for 4 weeks, followed by 0.5% cholesterol alone or supplemented with 2% L-arginine in drinking water during the next 12 weeks. Cholesterol feeding impaired endothelium-dependent relaxation of rabbit aortic rings ex vivo and increased urinary immunoreactive ET-1 excretion, along with decreased urinary nitrate excretion, an index of NO production. L-Arginine partially restored endothelium-dependent relaxation in parallel to increased urinary nitrate excretion and decreased urinary immunoreactive ET-1 excretion. Selective inhibition of ET-A receptors with BQ123 partially restored endothelium-dependent relaxation in hypercholesterolemic rabbits but had no effect on arterial rings from rabbits supplemented with L-arginine or from control animals. The contractile vascular response of aortic rings to exogenous ET-1 was increased in rabbits fed a high-cholesterol diet; this enhanced contractility to ET-1 was completely reversed by L-arginine. These data suggest that L-arginine restores endothelial function and normalizes the synthesis and vasoconstrictor response to ET-1 in hypercholesterolemia.

Topics: Animals; Arginine; Cholesterol; Cholesterol, Dietary; Creatine; Drug Interactions; Endothelin-1; Hypercholesterolemia; Male; Metabolic Clearance Rate; Nitrates; Rabbits; Vascular Resistance; Vasoconstriction

Peri-operative ischemic episodes following coronary artery bypass grafting with the internal mammary artery (IMA) are thought to be due to a vasospasm of this conduit. Endothelin-1 (ET-1) is a potent vasoconstrictor by itself and increases the response to other vasoconstrictor stimuli. This study focused on the possible role of an enhanced tissue ET-1-like immunoreactivity in the perioperative reaction of the IMA in patients with diabetes or hypercholesterolemia.. Specimens of the distal part of the IMA from 46 patients (mean age 58.5 years, four women, 42 men) were studied prospectively. Nine of those patients were diabetic and 26 had evidence of hypercholesterolemia. Another cohort of 20 IMA specimens was stained retrospectively; 10 of those biopsies were from patients that had experienced transient ischemic events peri-operatively in the myocardial area supplied by the IMA. The biopsies were examined histologically and immunohistochemically (rabbit polyclonal ET-1 antiserum, three-step avidin-biotin complex) with regard to their immunoreactivity to tissue ET-1.. An immunoreactivity to ET-1 (graded 0-3) was present in 89% of the biopsies. The reactivity was significantly higher in patients with hypercholesterolemia ( 1.92+/-0.74) when compared to controls (1.0+/-0.63) (P = 0.04). The reactivity was also increased in patients with non-insulin-dependent diabetes mellitus (2.1+/-0.79), when compared to controls (P = 0.02). Mostly transient ischemic events in the area supplied by the IMA seemed to occur more frequently when the biopsies revealed a higher immunoreactivity to ET-1. They showed an increased reactivity to ET-1 (2.27+/-0.76) compared to 10 patients with an uneventful peri-operative course (1.66+/-0.71 ) (P = 0.04).. This study provides evidence that the internal mammary artery is not a passive conduit. Vasospasm or vasoconstriction, in particular at its distal end, may occur more frequently in patients with hypercholesterolemia or diabetes, and may lead to post-operative ischemic events.

Topics: Biopsy; Cohort Studies; Coronary Circulation; Diabetes Mellitus, Type 2; Endothelin-1; Endothelium, Vascular; Female; Humans; Hypercholesterolemia; Immunohistochemistry; Internal Mammary-Coronary Artery Anastomosis; Intraoperative Complications; Male; Mammary Arteries; Middle Aged; Myocardial Ischemia; Prospective Studies; Retrospective Studies; Vasoconstriction; Vasoconstrictor Agents

Experimental hypercholesterolemia is associated with coronary vasomotor dysfunction. This study was designed to test the hypothesis that experimental hypercholesterolemia is characterized by altered coronary vasomotor responses to endothelin and inhibition of the endogenous NO pathway.. Endothelin-1 (ET-1) at 5 ng x kg(-1) x min(-1) or N(G)-monomethyl-L-arginine (L-NMMA), a competitive inhibitor of nitric oxide synthase (NOS), at 50 microg x kg(-1) x min(-1) was infused into the left anterior descending coronary artery in pigs before and after 10 weeks of cholesterol diet. There was a significant increase in serum cholesterol. At 10 weeks, ET-1 resulted in an accentuated decrease in coronary blood flow (CBF) and coronary artery diameter (CAD) compared with baseline (-88+/-6% versus -45+/-9%, P<.05, and -77+/-14% versus -18+/-8%, P<.05, respectively) and an increase in coronary vascular resistance (CVR) (242+/-18% versus 110+/-17%, P<.05); ET receptor density and binding affinity in epicardial coronary arteries were unchanged. The effect of L-NMMA on CBF, CAD, and CVR was attenuated at 10 weeks (-7+/-8% versus -48+/-4%, -2+/-3% versus -17+/-5%, and 16+/-10% versus 125+/-32%; each P<.05). Immunohistochemistry staining for constitutive NOS revealed a decrease in immunoreactivity in the coronary arteries of hypercholesterolemic pigs.. The present study demonstrates an enhanced coronary vasoconstrictive response to pathophysiological doses of endothelin and an attenuated response to the inhibition of endogenous NO activity, suggesting an alteration in coronary vascular reactivity in experimental hypercholesterolemia.

Topics: Acetylcholine; Animals; Binding, Competitive; Blood Pressure; Cardiac Output; Cholesterol, Dietary; Cholesterol, HDL; Cholesterol, LDL; Coronary Vessels; Endothelin-1; Enzyme Inhibitors; Female; Hemodynamics; Hypercholesterolemia; Nitric Oxide; omega-N-Methylarginine; Receptors, Endothelin; Swine; Vascular Resistance; Vasoconstriction

The coronary vasoconstrictor effects of endothelins, mediated by both endothelin ETA and ETB receptors, may be differentially altered in pathophysiological states associated with endothelial dysfunction and elevated endothelin levels. Experimental hypercholesterolemia is associated with coronary endothelial dysfunction and increased circulating endothelin concentrations. These studies were designed to test the hypothesis that experimental hypercholesterolemia is characterized by a differentially altered coronary contractile response to ETA- and ETB-receptor stimulation, in vitro. Pigs were fed either a normal or a high-cholesterol diet for 10 to 13 weeks. Changes in the intraluminal diameter of pressurized small coronary arteries (< 481 +/- 25 microns in diameter) to cumulative concentrations (10(-10) to 10(-6) mol/L) of endothelin-1 (ET-1), and sarafotoxin 6c (S6c), a specific ETB-receptor agonist, were measured using a video dimension analyzer. The maximal contraction attained with ET-1 was greater than with S6c in both normal (86 +/- 7% versus 47 +/- 7%, P = .001) and hypercholesterolemic (77 +/- 6% versus 37 +/- 7%, P < .001) pigs. At 10(-10) mol/L, vessels from hypercholesterolemic pigs manifested greater contraction to both ET-1 (23 +/- 6% versus 8 +/- 3%, P = .02) and S6c (17 +/- 5% versus 4 +/- 2%, P = .02). Incubation of arteries from hypercholesterolemic pigs with BQ-788 (ETB-receptor antagonist), but not FR-139317 (ETA-receptor antagonist), altered the contractile response to ET-1 at 10(-10) mol/L. Removal of the endothelium abolished the difference in response to S6c between normal and hypercholesterolemic pigs. These studies demonstrate that experimental hypercholesterolemia is characterized by enhanced coronary vasoconstriction to endothelins in vitro, the mechanism of which is mediated mainly through the ETB receptor. Thus, the ETB receptor has a role in regulation of coronary artery tone in both the steady-state and pathophysiological states.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Azepines; Cholesterol, Dietary; Coronary Vessels; Diet, Atherogenic; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Endothelium, Vascular; Female; Hypercholesterolemia; Indoles; Lipids; Oligopeptides; Piperidines; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Swine; Vasoconstriction; Vasoconstrictor Agents; Viper Venoms

The present study was designed to investigate the pattern of circulating endothelin-1 (ET-1), a potent vasoconstricting mitogenic endothelium-derived peptide, in relation to primary increase in serum cholesterol in humans. We measured plasma ET-1 concentrations by radioimmunoassay (Amersham, UK) in 8 patients (6 females and 2 males, aged 42-62 years) with primary hypercholesterolemia, non-smokers, without evidence of cardiovascular disease, and in 8 healthy sex-and age-matched control subjects. The mean (+/- SD) values of serum total cholesterol, low-density-lipoprotein (LDL) cholesterol, high-density-lipoprotein (HDL) cholesterol and triglycerides in the hypercholesterolemic subjects were 7.2 +/- 1.1 mmol/L, 5.1 +/- 1.1 mmol/L, 1.0 +/- 0.1 mmol/L and 2.4 +/- 0.9 mmol/L, respectively. The lipid profile of the controls showed a total cholesterol of 4.6 +/- 0.3 mmol/L, LDL cholesterol of 3.0 +/- 0.2 mmol/L, HDL cholesterol of 1.0 +/- 0.1 mmol/L and triglycerides of 1.2 +/- 0.2 mmol/L. The mean ET-1 plasma levels in the hypercholesterolemic patients were significantly higher than in the controls (4.2 +/- 0.1 pmol/L and 2.2 +/- 0.7 pmol/L, respectively, p < 0.001). Our data of raised circulating ET-1 in hypercholesterolemic patients without evidence of atherosclerosis suggest that an exaggerated release of ET-1 could contribute: 1) to impair endothelium-dependent vasodilation; 2) to promote the atherogenic process in hypercholesterolemia. Finally, it could represent a marker for hypercholesterolemic endothelial damage.

Topics: Adult; Cholesterol; Cholesterol, HDL; Cholesterol, LDL; Endothelin-1; Female; Humans; Hypercholesterolemia; Male; Middle Aged; Radioimmunoassay; Triglycerides

Our previous studies demonstrated the morphological heterogeneity of endothelial cells (ECs) and the emergence of large multinucleated ECs in human and animal atherosclerotic lesions. To investigate the functional alteration of ECs in diet-induced atherosclerosis, immunoreactive endothelin-1 (irET-1) release by ECs of the rabbit aorta was correlated with scanning electron microscopy. Rabbits were fed a cholesterol diet for 12 weeks: by scanning electron microscopy, the area of ECs in the aorta increased in the hypercholesterolemic (HC) group as atherosclerosis progressed. Cultured ECs of the HC group released significantly more irET-1 than ECs of the control. The plasma irET-1 level was also elevated in the HC group. The results obtained suggest that accelerated secretion of ET-1 by ECs contributes to the development of atherosclerotic vascular lesions.

Topics: Animals; Aorta, Thoracic; Cells, Cultured; Cholesterol; Cholesterol, Dietary; Diet, Atherogenic; Endothelin-1; Endothelium, Vascular; Humans; Hypercholesterolemia; Male; Microscopy, Electron, Scanning; Rabbits