3-nitrotyrosine and Hypertension

The aim of this study was to assess the effect of the angiotensin II receptor blocker Irbesartan on protein damage by glycation, oxidation and nitration in patients with type 2 diabetes and microalbuminuria. In a double-masked randomised crossover trial of 52 hypertensive type 2 diabetic patients, antihypertensive treatment was replaced with bendroflumethiazide. After 2-months wash-out, patients were treated randomly with Irbesartan 300, 600, and 900 mg o.d., each dose for 2 months in a three-way crossover study. Glycation, oxidation and nitration adduct residues in plasma protein and related urinary free adducts were determined by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry. Treatment with Irbesartan decreased urinary excretion of advanced glycation endproducts (AGEs)--methylglyoxal- and glyoxal-derived hydroimidazolones, MG-H1 and G-H1. Urinary AGEs were decreased by 30-32%. In plasma protein, treatment with Irbesartan increased content of glycation adducts Nε-fructosyl-lysine, AGEs Nε-carboxymethyl-lysine, Nε-carboxyethyl-lysine and pentosidine, and also increased content of oxidation markers N-formylkynurenine and dityrosine. This was attributed to decreased clearance of plasma protein modified by Nε-fructosyl-lysine and oxidative markers through the glomerular filter tightened by Irbesartan treatment. Treatment of patients with type 2 diabetes with Irbesartan decreased urinary excretion of MG-H1, G-H1 and 3-NT, which may result from decreased exposure to these AGEs. This is likely achieved by blocking angiotensin II signalling and related down-regulation of glyoxalase 1 and may contribute to health benefits of Irbesartan therapy.

Topics: Albuminuria; Amino Acids; Angiotensin II Type 1 Receptor Blockers; Antihypertensive Agents; Bendroflumethiazide; Biomarkers; Biphenyl Compounds; Cross-Over Studies; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Dose-Response Relationship, Drug; Female; Glycation End Products, Advanced; Glycosylation; Humans; Hypertension; Irbesartan; Male; Oxidative Stress; Tetrazoles; Tyrosine

Cyclosporin is a powerful stimulator of oxidative stress signaling, leading to TGFbeta production, NO degradation, endothelial dysfunction, hypertension and post-transplant nephropathy. Carvedilol, alpha1-beta-blocker with strong antioxidant activity, may interfere with this chain of events. Therefore, we measured monocyte ecNOS, TGFbeta and heme oxygenase-1 (HO-1) mRNA level and plasma nitrite/nitrate, 3-nitrotyrosine, an estimate of peroxynitrite, and total plasma antioxidant power in kidney-transplanted patients with post-transplant hypertension, before and after treatment with carvedilol, 25 - 50 mg o.d. orally for 4 months (n = 15). The dihydropyridine calcium channel blocker nifedipine (n = 10) was used as comparator antihypertensive drug. Blood pressure fell to a similar extent with both drugs. Carvedilol increased plasma antioxidant power and HO-1 mRNA and reduced 3-nitrotyrosine and TGFbeta mRNA levels, while the same was not observed with nifedipine. Monocyte ec NOS mRNA levels and plasma nitrite/nitrate were higher in the patients than in a normotensive healthy control group and were unaffected by either treatment. In conclusion, carvedilol reduces the oxidative stress and corrects the altered cellular signaling mediated by oxidative stress in CsA-induced post-transplant hypertension. Therefore, it may prevent long-term complications, such as endothelial dysfunction, fibrogenesis and post-transplant nephropathy by decreasing NO degradation and production of TGFbeta, a key fibrogenic cytokine, and by activating HO-1 production.

Topics: Adrenergic beta-Antagonists; Adult; Antihypertensive Agents; Blood Pressure; Calcium Channel Blockers; Carbazoles; Carvedilol; Cyclosporine; Drug Evaluation; Female; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Humans; Hypertension; Immunosuppressive Agents; Kidney Transplantation; Male; Membrane Proteins; Middle Aged; Nifedipine; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Oxidative Stress; Postoperative Complications; Propanolamines; RNA, Messenger; Signal Transduction; Transforming Growth Factor beta; Treatment Outcome; Tyrosine

In this pathbreaking study, we evaluated nitrosative stress in morbidly obese patients with and without metabolic syndrome. 62 women with class 3 obesity (BMI > 40 kg/m

Topics: Adult; Area Under Curve; Female; Glutathione; Glutathione Disulfide; Humans; Hypertension; Metabolic Syndrome; Middle Aged; Nitric Oxide; Nitrosative Stress; Obesity, Morbid; Oxidation-Reduction; Peroxidase; Peroxynitrous Acid; ROC Curve; Sulfhydryl Compounds; Tyrosine

Endothelial dysfunction accompanied by an increase in oxidative stress is a key event leading to hypertension. As dietary nitrite has been reported to exert antihypertensive effect, the present study investigated whether chronic oral administration of sodium nitrite improves vascular function in conduit and resistance arteries of hypertensive animals with elevated oxidative stress.. Sodium nitrite (50mg/L) was given to angiotensin II-infused hypertensive C57BL/6J (eight to ten weeks old) mice for two weeks in the drinking water. Arterial systolic blood pressure was measured using the tail-cuff method. Vascular responsiveness of isolated aortae and renal arteries was studied in wire myographs. The level of nitrite in the plasma and the cyclic guanosine monophosphate (cGMP) content in the arterial wall were determined using commercially available kits. The production of reactive oxygen species (ROS) and the presence of proteins (nitrotyrosine, NOx-2 and NOx-4) involved in ROS generation were evaluated with dihydroethidium (DHE) fluorescence and by Western blotting, respectively.. Chronic administration of sodium nitrite for two weeks to mice with angiotensin II-induced hypertension decreased systolic arterial blood pressure, reversed endothelial dysfunction, increased plasma nitrite level as well as vascular cGMP content. In addition, sodium nitrite treatment also decreased the elevated nitrotyrosine and NOx-4 protein level in angiotensin II-infused hypertensive mice.. The present study demonstrates that chronic treatment of hypertensive mice with sodium nitrite improves impaired endothelium function in conduit and resistance vessels in addition to its antihypertensive effect, partly through inhibition of ROS production.

Topics: Administration, Oral; Angiotensin II; Animals; Antihypertensive Agents; Antioxidants; Aorta, Thoracic; Arterial Pressure; Cyclic GMP; Disease Models, Animal; Endothelium, Vascular; Hypertension; Male; Mice, Inbred C57BL; NADPH Oxidase 2; NADPH Oxidase 4; Nitric Oxide; Oxidative Stress; Renal Artery; Sodium Nitrite; Tyrosine; Vasodilation

Chronic ethanol consumption is associated with hypertension and atherosclerosis. Vascular oxidative stress is described as an important mechanism whereby ethanol predisposes to atherosclerosis. We hypothesized that nebivolol would prevent ethanol-induced hypertension and vascular oxidative stress.. Male Wistar rats were treated with ethanol 20% (vol./vol.) or nebivolol (10 mg/kg/day, p. o., gavage), a selective β. The novelty of our study is that nebivolol prevented ethanol-induced hypertension and vascular oxidative stress. Additionally, we showed that the sympathetic nervous system (SNS) and the renin-angiotensin system (RAS) are important endogenous mediators of the cardiovascular effects of ethanol.

Topics: Adrenergic beta-1 Receptor Antagonists; Animals; Antihypertensive Agents; Aorta, Thoracic; Arterial Pressure; Biomarkers; Catalase; Disease Models, Animal; Epinephrine; Ethanol; Hypertension; Lipid Peroxidation; Male; NADPH Oxidases; Nebivolol; Nitric Oxide; Norepinephrine; Oxidative Stress; Rats, Wistar; Renin-Angiotensin System; Superoxide Dismutase; Sympathetic Nervous System; Tyrosine

Topics: Aconitate Hydratase; Animals; Antioxidants; Biofuels; Calcium-Binding Proteins; Chemokine CX3CL1; Cytokines; Dose-Response Relationship, Drug; Hypertension; Male; Microfilament Proteins; Microglia; Oxidative Stress; Rats; Rats, Inbred SHR; Rats, Inbred WKY; RNA, Messenger; Substantia Nigra; Tyrosine; Tyrosine 3-Monooxygenase; Vehicle Emissions

Hypertension is considered to be the most important risk factor for the development of cardiovascular diseases. Beside life-style risk factors, exposure to lead and mercury species are increasingly discussed as potential risk factors. Although there are a few previous studies, the underlying mechanism by which exposure to lead and mercury disturb blood pressure regulation is not currently understood. Potential mechanisms are oxidative stress production, kidney damage and activation of the renin-angiotensin system (RAS), all of which can interact to cause dysregulation of blood pressure. Male rats (Wistar) were exposed to lead, inorganic mercury, methylmercury or two mixtures of all three metals for four weeks through the drinking water. The two mixture ratios were based on ratios of known reference values or environmental exposure from the literature. To investigate the potential mechanism of actions, blood pressure was measured after four weeks and compared to plasma nitrotyrosine or reduced/oxidized glutathione levels in liver as markers for oxidative stress. Plasma renin and angiotensin II levels were used as markers for RAS activation. Finally, kidney function and injury were assessed via urinary and plasma creatinine levels, creatinine clearance and urinary kidney-injury molecule (KIM-1). While exposure to lead by itself increased oxidative stress and kidney damage along with blood pressure, inorganic mercury did not affect blood pressure or any end-point examined. Conversely, methylmercury instead increased RAS activation along with blood pressure. Surprisingly, when administered as mixtures, lead no longer increased oxidative stress or altered kidney function. Moreover, the mixture based on an environmental ratio no longer had an effect on blood pressure, while the reference value ratio still retained an increase in blood pressure. Based on our results, the prominent mechanism of action associated with the development of hypertension seems to be oxidative stress and kidney damage for lead, while increased RAS activation links methylmercury to hypertension, but these mechanisms along with hypertension disappear when metals are present in some mixtures.

Topics: Animals; Blood Pressure; Drinking Water; Glutathione; Hypertension; Kidney Diseases; Lead; Liver; Male; Mercury; Methylmercury Compounds; Oxidative Stress; Rats; Rats, Wistar; Renin-Angiotensin System; Tyrosine

Oxidative stress is involved in the development of carotid body (CB) chemosensory potentiation and systemic hypertension induced by chronic intermittent hypoxia (CIH), the main feature of obstructive sleep apnea. We tested whether peroxynitrite (ONOO(-)), a highly reactive nitrogen species, is involved in the enhanced CB oxygen chemosensitivity and the hypertension during CIH. Accordingly, we studied effects of Ebselen, an ONOO(-) scavenger, on 3-nitrotyrosine immunoreactivity (3-NT-ir) in the CB, the CB chemosensory discharge, and arterial blood pressure (BP) in rats exposed to CIH. Male Sprague-Dawley rats were exposed to CIH (5% O2, 12 times/h, 8 h/day) for 7 days. Ebselen (10 mg/kg/day) was administrated using osmotic minipumps and BP measured with radiotelemetry. Compared to the sham animals, CIH-treated rats showed increased 3-NT-ir within the CB, enhanced CB chemosensory responses to hypoxia, increased BP response to acute hypoxia, and hypertension. Rats treated with Ebselen and exposed to CIH displayed a significant reduction in 3-NT-ir levels (60.8 ± 14.9 versus 22.9 ± 4.2 a.u.), reduced CB chemosensory response to 5% O2 (266.5 ± 13.4 versus 168.6 ± 16.8 Hz), and decreased mean BP (116.9 ± 13.2 versus 82.1 ± 5.1 mmHg). Our results suggest that CIH-induced CB chemosensory potentiation and hypertension are critically dependent on ONOO(-) formation.

Topics: Animals; Azoles; Blood Pressure; Carotid Body; Diastole; Hypertension; Hypoxia; Isoindoles; Male; Neuronal Plasticity; Organoselenium Compounds; Peroxynitrous Acid; Rats, Sprague-Dawley; Systole; Tyrosine

Xanthine oxidase (XO) is an enzyme responsible for the production of uric acid. XO produces considerable amount of oxidative stress throughout the body. To date, however, its pathophysiologic role in hypertension and endothelial dysfunction still remains controversial. To explore the possible involvement of XO-derived oxidative stress in the pathophysiology of vascular dysfunction, by use of a selective XO inhibitor, febuxostat, we investigated the impact of pharmacological inhibition of XO on hypertension and vascular endothelial dysfunction in spontaneously hypertensive rats (SHRs). Sixteen-week-old SHR and normotensive Wistar-Kyoto (WKY) rats were treated with tap water (control) or water containing febuxostat (3 mg/kg/day) for 6 weeks. Systolic blood pressure (SBP) in febuxostat-treated SHR (220 ± 3 mmHg) was significantly (P < 0.05) decreased compared with the control SHR (236 ± 4 mmHg) while SBP in febuxostat-treated WKY was constant. Acetylcholine-induced endothelium-dependent relaxation in aortas from febuxostat-treated SHR was significantly (P < 0.05) improved compared with the control SHR, whereas relaxation in response to sodium nitroprusside was not changed. Vascular XO activity and tissue nitrotyrosine level, a representative indicator of local oxidative stress, were considerably elevated in the control SHR compared with the control WKY, and this increment was abolished by febuxostat. Our results suggest that exaggerated XO activity and resultant increase in oxidative stress in this experimental model contribute to the hypertension and endothelial dysfunction, thereby supporting a notion that pharmacological inhibition of XO is valuable not only for hyperuricemia but also for treating hypertension and related endothelial dysfunction in human clinics.

Topics: Animals; Antihypertensive Agents; Biomarkers; Blood Pressure; Disease Models, Animal; Endothelium, Vascular; Enzyme Inhibitors; Febuxostat; Hypertension; Male; Oxidative Stress; Rats, Inbred SHR; Rats, Inbred WKY; Time Factors; Tyrosine; Vasodilation; Vasodilator Agents; Xanthine Oxidase

Pulmonary arterial hypertension (PAH) is prevalent in patients with obstructive sleep apnea syndrome (OSAS). Aging induces arginase activation and reduces nitric oxide (NO) production in the arteries. Intermittent hypoxia (IH), conferred by cycles of brief hypoxia and normoxia, contributes to OSAS pathogenesis. Here, we studied the role of arginase and aging in the pathogenesis of PAH in adult (9-mo-old) and young (2-mo-old) male Sprague-Dawley rats subjected to IH or normoxia for 4 weeks and analyzed them with a pressure-volume catheter inserted into the right ventricle (RV) and by pulsed Doppler echocardiography. Western blot analysis was conducted on arginase, NO synthase isoforms, and nitrotyrosine. IH induced PAH, as shown by increased RV systolic pressure and RV hypertrophy, in adult rats but not in young rats. IH increased expression levels of arginase I and II proteins in the adult rats. IH also increased arginase I expression in the pulmonary artery endothelium and arginase II in the pulmonary artery adventitia. Furthermore, IH reduced pulmonary levels of nitrate and nitrite but increased nitrotyrosine levels in adult rats. An arginase inhibitor (N(ω)-hydroxy-nor-1-arginine) prevented IH-induced PAH and normalized nitrite and nitrate levels in adult rats. IH induced arginase up-regulation and PAH in adult rats, but not in young rats, through reduced NO production. Our findings suggest that arginase inhibition prevents or reverses PAH.

Topics: Aging; Animals; Arginase; Cell Hypoxia; Enzyme Activation; Hypertension; Lung; Male; Nitrates; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type III; Nitrites; Pulmonary Artery; Rats, Sprague-Dawley; Tyrosine

Recently, we demonstrated in female mice that protection against ANG II-induced hypertension and associated cardiovascular changes depend on cytochrome P-450 (CYP)1B1. The present study was conducted to determine if Cyp1b1 gene disruption ameliorates renal dysfunction and organ damage associated with ANG II-induced hypertension in female mice. ANG II (700 ng·kg(-1)·min(-1)) infused by miniosmotic pumps for 2 wk in female Cyp1b1(+/+) mice did not alter water consumption, urine output, Na(+) excretion, osmolality, or protein excretion. However, in Cyp1b1(-/-) mice, ANG II infusion significantly increased (P < 0.05) water intake (5.50 ± 0.42 ml/24 h with vehicle vs. 8.80 ± 0.60 ml/24 h with ANG II), urine output (1.44 ± 0.37 ml/24 h with vehicle vs. 4.30 ± 0.37 ml/24 h with ANG II), and urinary Na(+) excretion (0.031 ± 0.016 mmol/24 h with vehicle vs. 0.099 ± 0.010 mmol/24 h with ANG II), decreased osmolality (2,630 ± 79 mosM/kg with vehicle vs. 1,280 ± 205 mosM/kg with ANG II), and caused proteinuria (2.60 ± 0.30 mg/24 h with vehicle vs. 6.96 ± 0.55 mg/24 h with ANG II). Infusion of ANG II caused renal fibrosis, as indicated by an accumulation of renal interstitial α-smooth muscle actin, collagen, and transforming growth factor-β in Cyp1b1(-/-) but not Cyp1b1(+/+) mice. ANG II also increased renal production of ROS and urinary excretion of thiobarburic acid-reactive substances and reduced the activity of antioxidants and urinary excretion of nitrite/nitrate and the 17β-estradiol metabolite 2-methoxyestradiol in Cyp1b1(-/-) but not Cyp1b1(+/+) mice. These data suggest that Cyp1b1 plays a critical role in female mice in protecting against renal dysfunction and end-organ damage associated with ANG II-induced hypertension, in preventing oxidative stress, and in increasing activity of antioxidant systems, most likely via generation of 2-methoxyestradiol from 17β-estradiol.

Topics: Angiotensin II; Animals; Catalase; Cytochrome P-450 CYP1B1; Disease Models, Animal; Drinking; Estradiol; Female; Fibrosis; Genotype; Hypertension; Kidney; Kidney Diseases; Mice, Inbred C57BL; Mice, Knockout; NADPH Oxidases; Natriuresis; Oxidative Stress; Phenotype; Renin-Angiotensin System; Sex Factors; Superoxide Dismutase; Superoxides; Tyrosine; Urination

Angiotensin II (Ang II) and aldosterone contribute to hypertension, oxidative stress and cardiovascular damage, but the contributions of aldosterone during Ang II-dependent hypertension are not well defined because of the difficulty to assess each independently. To test the hypothesis that during Ang II infusion, oxidative and nitrosative damage is mediated through both the mineralocorticoid receptor (MR) and angiotensin type 1 receptor (AT1), five groups of Sprague-Dawley rats were studied: (i) control; (ii) Ang II infused (80 ng/min × 28 days); (iii) Ang II + AT1 receptor blocker (ARB; 10 mg losartan/kg per day × 21 days); (iv) Ang II + mineralocorticoid receptor (MR) antagonist (Epl; 100 mg eplerenone/day × 21 days); and (v) Ang II + ARB + Epl (Combo; × 21 days). Both ARB and combination treatments completely alleviated the Ang II-induced hypertension, whereas eplerenone treatment only prolonged the onset of the hypertension. Eplerenone treatment exacerbated the Ang II-mediated increase in plasma and heart aldosterone 2.3- and 1.8-fold, respectively, while ARB treatment reduced both. Chronic MR blockade was sufficient to ameliorate the AT1-mediated increase in oxidative damage. All treatments normalized protein oxidation (nitrotyrosine) levels; however, only ARB and Combo treatments completely reduced lipid peroxidation (4-hydroxynonenal) to control levels. Collectively, these data suggest that receptor signalling, and not the elevated arterial blood pressure, is the principal culprit in the oxidative stress-associated cardiovascular damage in Ang II-dependent hypertension.

Topics: Adrenal Glands; Aldehydes; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Biomarkers; Blood Pressure; Disease Models, Animal; Drug Therapy, Combination; Eplerenone; Heart Diseases; Hypertension; Lipid Peroxidation; Losartan; Male; Mineralocorticoid Receptor Antagonists; Myocardium; Oxidative Stress; Rats, Sprague-Dawley; Renin-Angiotensin System; Signal Transduction; Spironolactone; Time Factors; Tyrosine

Heart failure and related cardiac complications remains a great health challenge. We investigated the effects of upregulating heme-oxygenase (HO) on myocardial histo-pathological lesions, proinflammatory cytokines/chemokines, oxidative mediators and important markers of heart failure such as osteopontin and osteoprotergerin in N(ω)-nitro-l-arginine methyl ester (L-NAME)-induced hypertension. Treatment with the HO-inducer, heme-arginate improved myocardial morphology in L-NAME hypertensive rats by attenuating subendocardial injury, interstitial fibrosis, mononuclear-cell infiltration and cardiomyocyte hypertrophy. These were associated with the reduction of several inflammatory/oxidative mediators including chemokines/cytokines such as macrophage inflammatory protein-1 alpha (MIP-1α), macrophage chemoattractant protein-1 (MCP-1), tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, IL-1β, endothelin-1, 8-isoprostane, nitrotyrosine, and aldosterone. Similarly, heme-arginate abated the elevated levels of extracellular matrix/remodeling proteins including transforming-growth factor beta (TGF-β1) and collagen-IV in the myocardium. These were accompanied by significant reduction of proteins of heart failure such as osteopontin and osteoprotegerin. Interestingly, the cardio-protective effects of heme-arginate were associated with the potentiation of adiponectin, atrial-natriuretic peptide (ANP), HO-1, HO-activity, cyclic gnanosine monophosphate (cGMP) and the total-anti-oxidant capacity, whereas the HO-inhibitor, chromium-mesoporphyrin nullified the effects of heme-arginate, exacerbating inflammatory injury and oxidative insults. We conclude that heme-arginate therapy protects myocardial damage by potentiating the HO-adiponectin-ANP axis, which in turn suppressed the elevated levels of aldosterone, pro-inflammatory chemokines/cytokines, mononuclear-cell infiltration and oxidative stress, with concomitant reduction of extracellular matrix/remodeling proteins and heart failure proteins. These data suggest a cardio-protective role of the HO system against L-NAME-induced hypertension that could be explored in the design of novel strategies against cardiomyopathy.

Topics: Adiponectin; Aldosterone; Animals; Antioxidants; Arginine; Atrial Natriuretic Factor; Biomarkers; Blood Pressure; Cardiomyopathies; Cardiotonic Agents; Chemokine CCL2; Chemokine CCL3; Cyclic GMP; Dinoprost; Endothelin-1; Enzyme Induction; Extracellular Matrix Proteins; Heart Failure; Heme; Heme Oxygenase (Decyclizing); Hypertension; Interleukin-1beta; Interleukin-6; Male; NG-Nitroarginine Methyl Ester; Rats; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha; Tyrosine

Autoimmune activities have been implicated in the pathogenesis of hypertension. High levels of autoantibodies against the second extracellular loop of α1-adrenoceptor (α1-AR autoantibody, α1-AA) are found in patients with hypertension, and α1-AA could exert a α1-AR agonist-like vasoconstrictive effect. However, whether the vasoconstrictive effect of α1-AA is enhanced in hypertension is unknown. Using aortic rings of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats, we observed the vasoconstrictive responses to α1-AA with phenylephrine (α1-AR agonist) as a positive control drug. Aortic nitrotyrosine levels were also measured by ELISA and immunohistochemistry. The results showed that the aortic constrictive responses to α1-AA and phenylephrine (both 1 nmol L(-1)-10 μmol L(-1)) were greater in SHR than in WKY rats. Endothelial denudation or L-NAME (a non-selective NOS inhibitor) (100 μmol L(-1)) increased α1-AA- or phenylephrine-induced vasoconstrictions both in SHR and WKY. However, selective iNOS inhibitor 1400 W (10 μmol L(-1)) enhanced the α1-AA-induced aortic constriction in WKY, but not in SHR. The aortic nitrotyrosine level was significantly higher in SHR than WKY, as shown by both ELISA and immunohistochemistry. These results indicate that the vasoconstrictive response to α1-AA is enhanced in SHR, and this altered responsiveness is due to endothelial dysfunction and decreased NO bioavailability. The study suggests an important role of α1-AR autoimmunity in the pathogenesis and management of hypertension especially in those harboring high α1-AA levels.

Topics: Adrenergic alpha-1 Receptor Agonists; Animals; Aorta; Autoantibodies; Blotting, Western; Dose-Response Relationship, Drug; Endothelium, Vascular; Enzyme Inhibitors; Humans; Hypertension; In Vitro Techniques; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Phenylephrine; Rats, Inbred SHR; Rats, Inbred WKY; Rats, Wistar; Receptors, Adrenergic, alpha-1; Tyrosine; Vasoconstriction; Vasoconstrictor Agents

Chronic arsenic exposure has been linked to elevated blood pressure and cardiovascular diseases, while statins reduce the incidence of cardiovascular disease predominantly by their low density lipoprotein-lowering effect. Besides, statins have other beneficial effects, including antioxidant and anti-inflammatory activities. We evaluated whether atorvastatin, a widely used statin, can ameliorate arsenic-induced increase in blood pressure and alteration in lipid profile and also whether the amelioration could relate to altered NO and ROS signaling. Rats were exposed to sodium arsenite (100ppm) through drinking water for 90 consecutive days. Atorvastatin (10mg/kg bw, orally) was administered once daily during the last 30days of arsenic exposure. On the 91st day, blood was collected for lipid profile. Western blot of iNOS and eNOS protein, NO and 3-nitrotyrosine production, Nox-4 and p22Phox mRNA expression, Nox activity, ROS generation, lipid peroxidation and antioxidants were evaluated in thoracic aorta. Arsenic increased systolic, diastolic and mean arterial blood pressure, while it decreased HDL-C and increased LDL-C, total cholesterol and triglycerides in serum. Arsenic down-regulated eNOS and up-regulated iNOS protein expression and increased basal NO and 3-nitrotyrosine level. Arsenic increased aortic Nox-4 and p22Phox mRNA expression, Nox activity, ROS generation and lipid peroxidation. Further, arsenic decreased the activities of superoxide dismutase, catalase, and glutathione peroxidase and depleted aortic GSH content. Atorvastatin regularized blood pressure, improved lipid profile and attenuated arsenic-mediated redox alterations. The results demonstrate that atorvastatin has the potential to ameliorate arsenic-induced hypertension by improving lipid profile, aortic NO signaling and restoring vascular redox homeostasis.

Topics: Animals; Aorta, Thoracic; Arsenites; Atorvastatin; Catalase; Cholesterol; Glutathione Peroxidase; Heptanoic Acids; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypertension; Male; NADPH Oxidase 4; NADPH Oxidases; Nitric Oxide; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Oxidative Stress; Pyrroles; Random Allocation; Rats, Wistar; Real-Time Polymerase Chain Reaction; RNA, Messenger; Sodium Compounds; Superoxide Dismutase; Tyrosine

Oxidative stress seems to play an important role in the pathophysiology of essential hypertension. We aimed to examine serum MDA, NO, 8-OHdG, ADMA, NT, CoQ10 and TAC as biomarkers of oxidative stress in dipper and non-dipper hypertensive patients.. Eighteen dipper hypertensives, 20 non-dipper hypertensives and 22 healthy control subjects were included in the study. Clinical assessment and ambulatory blood pressure monitoring were performed in patients. Serum MDA, TAC and NO levels were measured by using spectrophotometric methods. CoQ10 levels were measured by HPLC method. 8-OHdG, ADMA and NT were quantitated by ELISA methods.. MDA levels were significantly higher in dipper and non-dipper groups compared to controls (p<0.05 and p<0.01, respectively). TAC levels were found at low level in patients dipper and non-dipper patients compared to control group (p<0.01). Higher ADMA and NT levels but lower CoQ10 levels were found in non-dipper group compared to healthy controls (p<0.01, p<0.05, and p<0.05, respectively). ADMA levels were found higher in non-dipper group than those of dipper group (p<0.01).. Increased ADMA, NT levels and decreased CoQ10 levels in non-dipper hypertensive patients might indicate more severe oxidative stres compared with dipper hypertensive patients, which plays an important role in the development of cardiovascular diseases. Increased MDA and reduced TAC levels might be considered as prospective prognostic markers of the development of cardiovascular diseases in dipper and non-dipper hypertensive patients.

Topics: Antioxidants; Arginine; Biomarkers; Blood Pressure; Blood Pressure Monitoring, Ambulatory; Circadian Rhythm; Female; Humans; Hypertension; Male; Malondialdehyde; Middle Aged; Oxidative Stress; Prospective Studies; Tyrosine

This study was designed to evaluate the in vivo cardioprotective effects of food-derived sesamin in spontaneously hypertensive rats (SHR). The study was performed with 17-week-old male normotensive Wistar-Kyoto rats (WKY) and SHR which are untreated or treated with orally administered sesamin for 16 weeks before they were sacrificed. Long-term treatment with sesamin obviously improved left ventricular (LV) hypertrophy and fibrosis in SHR, as indicated by the decrease of LV weight/body weight, myocardial cell size, cardiac fibrosis and collagen type I expression as well as the amelioration of the LV ultrastructure. These effects were associated with reduced systolic blood pressure, enhanced cardiac total antioxidant capability and decreased malondialdehyde content, nitrotyrosine level and transforming growth factor β1 (TGF-β1) expression. All these results suggest that chronic treatment with sesamin improves LV remodeling in SHR through alleviation of oxidative and nitrative stress, reduction of blood pressure and downregulation of TGF-β1 expression.

Topics: Animals; Antihypertensive Agents; Blood Pressure; Collagen Type I; Dioxoles; Disease Models, Animal; Down-Regulation; Fibrosis; Heart; Hypertension; Hypertrophy, Left Ventricular; Lignans; Male; Malondialdehyde; Myocytes, Cardiac; Rats; Rats, Inbred SHR; Rats, Inbred WKY; RNA, Messenger; Transforming Growth Factor beta1; Tyrosine; Ventricular Remodeling

The current study was designed to test the hypothesis that inducible nitric oxide synthase (iNOS)-mediated lipid free radical overproduction exists in an insulin-resistant rat model and that reducing the accumulation of toxic metabolites is associated with improved insulin signaling and metabolic response. Lipid radical formation was detected by electron paramagnetic resonance spectroscopy with in vivo spin trapping in an obese rat model, with or without thiazolidinedione treatment. Lipid radical formation was accompanied by accumulation of toxic end products in the liver, such as 4-hydroxynonenal and nitrotyrosine, and was inhibited by the administration of the selective iNOS inhibitor 1400 W. The model showed impaired phosphorylation of the insulin signaling pathway. Ten-day rosiglitazone injection not only improved the response to an oral glucose tolerance test and corrected insulin signaling but also decreased iNOS levels. Similar to the results with specific iNOS inhibition, thiazolidinedione dramatically decreased lipid radical formation. We demonstrate a novel mechanism where a thiazolidinedione treatment can reduce oxidative stress in this model through reducing iNOS-derived lipid radical formation. Our results suggest that hepatic iNOS expression may underlie the accumulation of lipid end products and that reducing the accumulation of toxic lipid metabolites contributes to a better redox status in insulin-sensitive tissues.

Topics: Aldehydes; Animals; Body Composition; Free Radicals; Glucose Intolerance; Heart Failure; Hypertension; Insulin Resistance; Lipid Peroxidation; Liver; Male; Muscle, Skeletal; Nitric Oxide Synthase Type II; Nitrites; Oxidative Stress; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Thiazolidinediones; Tyrosine

NADPH oxidases constitute a major source of superoxide anion (·O(2)(-)) in hypertension. Several studies suggest an important role of NADPH oxidases in different effects mediated by TGF-β 1. In this study we show that chronic administration of P144, a peptide synthesized from type III TGF-β 1 receptor, significantly reduced the cardiac NADPH oxidase expression and activity as well as in the nitrotyrosine levels observed in control spontaneously hypertensive rats (V-SHR) to levels similar to control normotensive Wistar Kyoto rats. In addition, P144 was also able to reduce the significant increases in the expression of collagen type I protein and mRNA observed in hearts from V-SHR. In addition, positive correlations between collagen expression, NADPH oxidase activity, and nitrotyrosine levels were found in all animals. Finally, TGF-β 1-stimulated Rat-2 exhibited significant increases in NADPH oxidase activity that was inhibited in the presence of P144. It could be concluded that the blockade of TGF-β 1 with P144 inhibited cardiac NADPH oxidase in SHR, thus adding new data to elucidate the involvement of this enzyme in the profibrotic actions of TGF-β 1.

Topics: Animals; Blood Pressure; Cell Line; Collagen Type I; Fibroblasts; Heart; Hypertension; Male; Membrane Glycoproteins; Myocardium; NADPH Oxidase 2; NADPH Oxidase 4; NADPH Oxidases; Peptide Fragments; Rats; Rats, Inbred WKY; Receptors, Transforming Growth Factor beta; Signal Transduction; Transforming Growth Factor beta1; Tyrosine

Hypertension and diabetes are known risk factors for retinal microvascular damage. However, the combined effects of diabetes with early and established stages of hypertension on retinal microvascular degeneration remain incompletely understood.. Male spontaneously hypertensive rats (SHR) were compared to SHR with streptozotocin-induced diabetes (SHR+D) for 6 or 10 weeks and Wistar rats as controls.. Hypertension alone (the SHR group) or in combination with diabetes (the SHR+D group) for 6 weeks induced additive increases in total retinal cell death, compared to the Wistar controls. This increase was associated with significant increases in phosphorylated-Jun N-terminal kinase (pJNK) activation, phosphorylated-Akt inhibition, plasma and retinal lipid peroxides, and soluble intracellular adhesion molecule-1 (sICAM-1) levels. After 10 weeks, a similar trend was still observed in retinal nitrotyrosine, nuclear factor kappaB p65, and tumor necrosis factor-α expression, associated with exacerbated pJNK activation and formation of acellular capillaries.. In conclusion, combining diabetes and hypertension-potentiated retinal oxidative/inflammatory stress promoted imbalance between the JNK stress and survival Akt pathways resulting in accelerated retinal cell death and acellular capillary formation.

Topics: Animals; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Gene Expression; Hypertension; Inflammation; Intercellular Adhesion Molecule-1; Lipid Peroxidation; Male; MAP Kinase Kinase 4; NF-kappa B; Oxidative Stress; Phosphorylation; Proto-Oncogene Proteins c-akt; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Retina; Retinal Neovascularization; Tumor Necrosis Factor-alpha; Tyrosine

In the present study, we tested whether polycystic kidney disease (PKD) is associated with renal tissue hypoxia and oxidative stress, which, in turn, contribute to the progression of cystic disease and hypertension. Lewis polycystic kidney (LPK) rats and Lewis control (Lewis) rats were treated with tempol (1 mmol/L in drinking water) from 3 to 13 weeks of age or remained untreated. The LPK rats developed polyuria, uraemia and proteinuria. At 13 weeks of age, LPK rats had greater mean arterial pressure (1.5-fold), kidney weight (sixfold) and plasma creatinine (3.5-fold) than Lewis rats. Kidneys from LPK rats were cystic and fibrotic. Renal hypoxia was evidenced by staining for pimonidazole adducts and hypoxia-inducible factor (HIF)-1α in cells lining renal cysts and upregulation of HIF-1α and its downstream targets vascular endothelial growth factor (VEGF), glucose transporter-1 (Glut-1) and heme oxygenase 1 (HO-1). However, total HO activity did not differ greatly between kidney tissue from LPK compared with Lewis rats. Renal oxidative and/or nitrosative stress was evidenced by ninefold greater immunofluorescence for 3-nitrotyrosine in kidney tissue from LPK compared with Lewis rats and a > 10-fold upregulation of mRNA for p47phox and gp91phox. Total renal superoxide dismutase (SOD) activity was sevenfold less and expression of SOD1 mRNA was 70% less in kidney tissue from LPK compared with Lewis rats. In LPK rats, tempol treatment reduced immunofluorescence for 3-nitrotyrosine and HIF1A mRNA while upregulating VEGF and p47phox mRNA expression, but otherwise had little impact on disease progression, renal tissue hypoxia or hypertension. Our findings do not support the hypothesis that oxidative stress drives hypoxia and disease progression in PKD.

Topics: Animals; Arterial Pressure; Cell Hypoxia; Creatinine; Cyclic N-Oxides; Disease Progression; Glucose Transporter Type 1; Heme Oxygenase (Decyclizing); Hemodynamics; Hypertension; Hypoxia-Inducible Factor 1, alpha Subunit; Kidney; Kidney Diseases; Male; Membrane Glycoproteins; NADPH Oxidase 2; NADPH Oxidases; Oxidative Stress; Polycystic Kidney Diseases; Rats; Rats, Inbred Lew; Spin Labels; Superoxide Dismutase; Superoxide Dismutase-1; Tyrosine; Vascular Endothelial Growth Factor A

in this study we have assessed the renal and cardiac consequences of ligature-induced periodontitis in both normotensive and nitric oxide (NO)-deficient (L-NAME-treated) hypertensive rats.. oral L-NAME (or water) treatment was started two weeks prior to induction of periodontitis. Rats were sacrificed 3, 7 or 14 days after ligature placement, and alveolar bone loss was evaluated radiographically. Thiobarbituric reactive species (TBARS; a lipid peroxidation index), protein nitrotyrosine (NT; a marker of protein nitration) and myeloperoxidase activity (MPO; a neutrophil marker) were determined in the heart and kidney.. in NO-deficient hypertensive rats, periodontitis-induced alveolar bone loss was significantly diminished. In addition, periodontitis-induced cardiac NT elevation was completely prevented by L-NAME treatment. On the other hand L-NAME treatment enhanced MPO production in both heart and kidneys of rats with periodontitis. No changes due to periodontitis were observed in cardiac or renal TBARS content.. in addition to mediating alveolar bone loss, NO contributes to systemic effects of periodontitis in the heart and kidney.

Topics: Alveolar Bone Loss; Animals; Disease Models, Animal; Enzyme Inhibitors; Free Radical Scavengers; Heart; Hypertension; Kidney; Male; Myocardium; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Oxidative Stress; Periodontitis; Peroxidase; Radiography; Rats; Rats, Wistar; Thiobarbituric Acid Reactive Substances; Tyrosine

Asymmetric dimethylarginine (ADMA) is an endogenous modulator of endothelial function and oxidative stress, and increased levels of this molecule have been reported in some metabolic disorders and cardiovascular diseases. The aim of this work was to analyze the time course of dimethylarginine compounds and oxidative stress levels and the relationship between these and cardiovascular function in fructose-hypertensive rats.. 90 male Sprague-Dawley rats were randomized into 2 groups, fed for 3 months with standard (C) chow supplemented or not with fructose (F, 60%). After sacrifice at different weeks (W), the aorta and plasma were harvested to assess the vascular and biochemical parameters. Our work showed that the plasma levels of ADMA in the fructose-fed rats increased after 2 weeks of the diet (1.6 ± 0.3 μM vs. 1.2 ± 0.3 μM, p < 0.05) with no changes in plasma levels of either SDMA or L-arginine and after an increase in glycemia. Levels of vascular oxidative stress, estimated in aortic segments using an oxidative fluorescence technique, were higher in the F group (W2: 1.14 ± 0.2% vs. 0.33 ± 0.02%, p < 0.01). An increase in expression levels of nitrotyrosine (3-fold) and iNOS (2-fold) were noted in the fructose-fed rats. After 1 month, this was associated with a significant increase in NAD(P)H oxidase activity. Concerning vascular function, a 15% decrease in maximal endothelium-dependent relaxation was found in the aorta of the F group. Our work showed that the presence of exogenous L-MMA, an inhibitor of NO synthase, was associated with a significant reduction in endothelium-dependent relaxation in isolated aorta rings of the C group; this effect was not observed in the vessels of fructose-fed rats.. Our findings suggest that the elevated levels of ADMA observed could in part be secondary to the early development of oxidative stress associated with the development of hypertension.

Topics: Animals; Aorta; Arginine; Blood Glucose; Blood Pressure; Body Weight; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Fructose; Heart Rate; Hypertension; Male; Metabolic Syndrome; NADPH Oxidases; Nitric Oxide Synthase Type II; Oxidative Stress; Rats; Rats, Sprague-Dawley; Time Factors; Tyrosine; Vasodilation; Vasodilator Agents

Renal resistive index is a useful measure for quantifying alterations in renal blood flow. In the present study we evaluated resistive index at baseline and after vasodilation induced by nitroglycerine in normoalbuminuric patients with type 2 diabetes or essential hypertension, relating the values to indices of systemic vascular dysfunction.. Newly diagnosed treatment-naïve type 2 diabetic (n = 32) and hypertensive patients (n = 49) were compared with 27 age- and sex-matched healthy controls. Renal resistive index was obtained by duplex ultrasound at baseline and after 25 μg sublingual nitroglycerine. Endothelium-dependent (flow-mediated dilation) and -independent (response to nitroglycerine) vasodilation in the brachial artery was assessed by computerised edge detection system. Carotid-femoral pulse-wave velocity and augmentation index were assessed by applanation tonometry. Nitrotyrosine levels, an index of oxidative stress, were also measured.. Resistive index was higher in diabetic than in hypertensive patients and controls (p < 0.001), while changes in resistive index induced by nitroglycerine were lower in hypertensive patients compared with controls (p < 0.01), and were further reduced in type 2 diabetic patients. Hypertensive and diabetic patients showed significantly increased arterial stiffness, nitrotyrosine levels and reduced endothelial function than controls (p < 0.05). Changes in resistive index induced by nitroglycerine were independently related to serum glucose, reactive hyperaemia and aortic pulse-wave velocity in the overall population.. These results support the dynamic evaluation of renal resistive index as an early detector of renal vascular alterations in the presence of type 2 diabetes and hypertension, even before the onset of microalbuminuria.

Topics: Adult; Albuminuria; Blood Glucose; Case-Control Studies; Comorbidity; Diabetes Mellitus, Type 2; Female; Humans; Hypertension; Kidney; Male; Middle Aged; Nitroglycerin; Oxidative Stress; Regional Blood Flow; Tyrosine; Ultrasonography; Vasodilation; Vasodilator Agents

The present study was aimed to determine whether there is an altered role of local nitric oxide (NO) and atrial natriuretic peptide (ANP) systems in the kidney in association with the angiotensin (Ang) II-induced hypertension. Male Sprague-Dawley rats were used. Ang II (100 ng·min⁻¹·kg⁻¹) was infused through entire time course. Thirteenth day after beginning the regimen, kidneys were taken. The protein expression of NO synthase (NOS) and nitrotyrosine was determined by semiquantitative immunoblotting. The mRNA expression of components of ANP system was determined by real-time polymerase chain reaction. The activities of soluble and particulate guanylyl cyclases were determined by the amount of cGMP generated in responses to sodium nitroprusside and ANP, respectively. There developed hypertension and decreased creatinine clearance in the experimental group. The protein expression of eNOS, nNOS and nitrotyrosine was increased in the cortex, while that of iNOS remained unaltered. The urinary excretion of NO increased in Ang II-induced hypertensive rats. The catalytic activity of soluble guanylyl cyclase was blunted in the glomerulus in Ang II-induced hypertensive rats. The mRNA expression of ANP was increased in Ang II-induced hypertensive rats. Neither the expression of NPR-A nor that of NPR-C was changed. The protein expression of neutral endopeptidase was decreased and the activity of particulate guanylyl cyclase was blunted in the glomerulus and papilla in Ang II-induced hypertensive rats. In conclusion, the synthesis of NO and ANP was increased in the kidney of Ang II-induced hypertension, while stimulated cGMP response was blunted. These results suggest desensitization of guanylyl cyclase in the kidney of Ang II-induced hypertensive rats, which may contribute to the associated renal vasoconstriction and hypertension.

Topics: Angiotensin II; Animals; Atrial Natriuretic Factor; Blood Pressure; Cyclic GMP; Hypertension; Kidney; Kidney Function Tests; Male; Neprilysin; Nitric Oxide; Nitric Oxide Synthase; Rats; Rats, Sprague-Dawley; Transcription, Genetic; Tyrosine

Endothelial dysfunction is a hallmark of hypertension and vascular oxidative stress can contribute to endothelial dysfunction and hypertension development. Resveratrol is an antioxidant polyphenol which improves endothelium dependent relaxation, the mechanisms of which are unknown. Also, the role of resveratrol in hypertension remains to be established. The purpose of this study was to investigate the mechanisms of resveratrol induced improvement of endothelial function and establish its role in hypertension. SHR and WKY rats, 3-4 weeks old, were treated with resveratrol in drinking water for 10 weeks, untreated SHR and WKY rats served as controls. At the end of the treatment, control SHR exhibited increased blood pressure, oxidative stress and attenuated endothelium dependent relaxation in comparison to WKY rats. The impaired endothelium function in SHR was associated with lower nitrite/nitrate levels, elevated nitrotyrosine content and eNOS uncoupling. Resveratrol treatment attenuated hypertension development in SHR as indicated by lower blood pressure in resveratrol treated SHR (SHR-R) compared to control SHR. SHR-R also exhibited reduced H(2)O(2) content and elevated superoxide dismutase activity. Resveratrol treatment normalized endothelium dependent vasorelaxation in SHR. In parallel, resveratrol restored nitrite/nitrate levels and normalized nitrotyrosine content in SHR. SHR exhibited increased l-arginine dependent superoxide production which was blocked by NOS inhibitor l-NNA, suggesting eNOS uncoupling. eNOS uncoupling was prevented by resveratrol treatment. In conclusion, early treatment with resveratrol lowers oxidative stress, preserves endothelial function and attenuates development of hypertension in SHR. More importantly, prevention of eNOS uncoupling and NO scavenging could represent novel mechanisms for resveratrol-mediated antihypertensive effects.

Topics: Animals; Antioxidants; Blood Pressure; Body Weight; Drinking; Eating; Endothelium, Vascular; Heart; Hypertension; Male; Nitric Oxide; Nitric Oxide Synthase Type III; Organ Size; Oxidative Stress; Rats; Rats, Inbred SHR; Resveratrol; Stilbenes; Tyrosine

The optimum antihypertensive treatment for prevention of hypertensive stroke has yet to be elucidated. This study was undertaken to examine the benefit of a combination of valsartan, an angiotensin II type 1 (AT1) receptor blocker, and amlodipine, a calcium channel blocker, in prevention of high-salt-induced brain injury in hypertensive rats. High-salt-loaded stroke-prone spontaneously hypertensive rats (SHRSPs) were given 1) vehicle, 2) valsartan (2 mg/kg/day), 3) amlodipine (2 mg/kg/day), or 4) a combination of valsartan and amlodipine for 4 weeks. The effects on brain injury were compared between all groups. High-salt loading in SHRSPs caused the reduction of cerebral blood flow (CBF), cerebral hypoxia, white matter lesions, glial activation, AT1 receptor up-regulation, endothelial nitric-oxide synthase (eNOS) uncoupling, inducible nitric-oxide synthase induction, and nitroxidative stress. Valsartan, independently of blood pressure, enhanced the protective effects of amlodipine against brain injury, white matter lesions, and glial activation in salt-loaded SHRSPs. These beneficial effects of valsartan added to amlodipine were associated with an additive improvement in CBF and brain hypoxia because of an additive improvement in cerebral arteriolar remodeling and vascular endothelial dysfunction. Furthermore, valsartan added to amlodipine enhanced the attenuation of cerebral nitroxidative stress through an additive suppression of eNOS uncoupling. Valsartan, independently of blood pressure, augmented the protective effects of amlodipine against brain injury in salt-loaded hypertensive rats through an improvement in brain circulation attributed to nitroxidative stress. Our results suggest that the combination of valsartan and amlodipine may be a promising strategy for the prevention of salt-related brain injury in hypertensive patients.

Topics: Amlodipine; Angiotensin II Type 1 Receptor Blockers; Animals; Blood Pressure; Brain; Calcium Channel Blockers; Calcium Channels; Carotid Arteries; Drug Therapy, Combination; Endothelial Cells; Hypertension; Hypoxia-Ischemia, Brain; Male; Nitric Oxide; Nitric Oxide Synthase Type III; Random Allocation; Rats; Rats, Inbred SHR; Receptor, Angiotensin, Type 1; Sodium Chloride, Dietary; Tetrazoles; Tyrosine; Valine; Valsartan

Systemic diseases affect skeletal muscle, and inflammation and oxidative stress are some of the involved mechanisms. There is scarce information about the effects of essential hypertension on skeletal muscle. The soleus and extensor digitorum longus (EDL) muscles of spontaneously hypertensive rats (SHR) were studied compared to control Wistar Kyoto (WKY) rats. The levels of nitrite and nitrate in micromol/mg-protein; endothelial (eNOS), neuronal (nNOS), and inducible (iNOS) nitric oxide synthases, nitrotyrosine and tumour necrosis factor alpha (TNF-alpha) in ng/mg-protein were determined. Compared with controls, the SHR showed increased levels of nitrotyrosine (soleus 24.4 +/- 5.0 vs. 3.3 +/- 0.3, p<0.001; EDL 20.2 +/- 4.3 vs. 4.5 +/- 0.4, p<0.0037), iNOS (soleus 26.6 +/- 3.7 vs. 8.3 +/- 0.9; EDL 21.3 +/- 3.7 vs. 11.0 +/- 0.8, both p<0.0001) and TNF-alpha (soleus 2.2 +/- 0.5 vs. 0.6 +/- 0.1, p<0.05; EDL 1.9 +/- 0.2 vs. 0.6 +/- 0.1, p<0.02). A decrease of eNOS was found in soleus muscle (20.6 +/- 1.4 vs. 30.3 +/- 1.2, p<0.00001); of nNOS (soleus 16.8 +/- 1.4 vs. 20.7 +/- 1.8, p< 0.05; EDL 13.6 +/- 1.3 vs. 21.9 +/- 1.8, p<.005) and nitrite in EDL (5.8 +/- 0.3 vs. 7.1 +/- 0.5, p<0.026).There was a positive correlation between TNF-alpha vs. nitrotyrosine in soleus (r=0.798; p<0.031) and a tendency in EDL (r=0.739; p=0.059); iNOS vs. nitrotyrosine (soleus: r=0.908; p<0.0001; EDL: r=0.707; p<0.01), a tendency between TNF-alpha and iNOS (EDL: r=0.736; p<0.059); and a negative correlation between eNOS vs. nitrotyrosine in soleus muscle (r=-0.816; p<0.0012). In conclusion, in skeletal muscles of SHR an inflammatory process was found evidenced by the increase in TNF-alpha, nitrotyrosine and iNOS. The decreased levels of constitutive synthases, together with the higher level of iNOS, are indicative of endothelial dysfunction.

Topics: Animals; Endothelium, Vascular; Hypertension; Male; Muscle, Skeletal; Myositis; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Oxidative Stress; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Tumor Necrosis Factor-alpha; Tyrosine

Intermittent hypoxia, a feature of obstructive sleep apnoea, potentiates ventilatory hypoxic responses, alters heart rate variability and produces hypertension, partially owing to an enhanced carotid body responsiveness to hypoxia. Since oxidative stress is a potential mediator of both chemosensory and cardiorespiratory alterations, we hypothesised that an antioxidant treatment may prevent these alterations. Accordingly, we studied the effects of ascorbic acid (1.25 g.L(-1) drinking water) on plasma lipid peroxidation, nitrotyrosine and inducible nitric oxide synthase (iNOS) immunoreactivity in the carotid body, ventilatory and carotid chemosensory responses to acute hypoxia, heart rate variability and arterial blood pressure in male Sprague-Dawley rats exposed to 5% O(2); 12 episodes.h(-1); 8 h.day(-1) or sham condition for 21 days. Intermittent hypoxia increased plasma lipid peroxidation, nitrotyrosine and iNOS expression in the carotid body, enhanced carotid chemosensory and ventilatory hypoxic responses, modified heart rate variability and produced hypertension. Ascorbic acid prevented the increased plasma lipid peroxidation and nitrotyrosine formation within the carotid body, and the enhanced carotid chemosensory and ventilatory responses to hypoxia, as well as heart rate variability alterations and hypertension. The present results support an essential role for oxidative stress in the generation of carotid body chemosensory potentiation and systemic cardiorespiratory alterations induced by intermittent hypoxia.

Topics: Animals; Antioxidants; Ascorbic Acid; Carotid Body; Chemoreceptor Cells; Heart Rate; Hypertension; Hypoxia; Lipid Peroxidation; Lipids; Male; Malondialdehyde; Nitric Oxide Synthase Type II; Nitrosamines; Oxidative Stress; Pulmonary Ventilation; Rats; Sleep Apnea, Obstructive; Tyrosine

Renin-angiotensin system (RAS) activation contributes to kidney injury through oxidative stress. Renin is the rate-limiting step in angiotensin (ANG II) generation. Recent work suggests renin inhibition improves proteinuria comparable to ANG type 1 receptor (AT1R) blockade (ARB). Thereby, we investigated the relative impact of treatment with a renin inhibitor vs. an ARB on renal oxidative stress and associated glomerular structural and functional changes in the transgenic Ren2 rat, which manifests hypertension, albuminuria, and increased tissue RAS activity. Young Ren2 and age-matched Sprague-Dawley (SD) controls (age 6-9 wk) were treated with a renin inhibitor (aliskiren), an ARB (irbesartan), or vehicle for 21 days. Ren2 rats exhibited increases in systolic pressure (SBP), albuminuria, and renal 3-nitrotyrosine content as well as ultrastructural podocyte foot-process effacement and diminution of the podocyte-specific protein nephrin. Structural and functional alterations were accompanied by increased renal cortical ANG II, AT1R, as well as NADPH oxidase subunit (Nox2) expression compared with SD controls. Abnormalities were attenuated to a similar extent with both aliskiren and irbesartan treatment. Despite the fact the dose of irbesartan used caused a greater reduction in SBP than aliskerin treatment (P < 0.05), the effects on proteinuria, nephrin, and oxidative stress were similar between the two treatments. Our results highlight both the importance of pressor-related reductions on podocyte integrity and albuminuria as well as RAS-mediated oxidant stress largely comparable between ARB and renin inhibition treatment.

Topics: Albuminuria; Amides; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Biphenyl Compounds; Blood Pressure; Fumarates; Glomerular Filtration Rate; Hypertension; Irbesartan; Kidney; Membrane Glycoproteins; Membrane Proteins; NADPH Oxidase 2; NADPH Oxidases; Oxidative Stress; Podocytes; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Receptor, Angiotensin, Type 1; Renin; Renin-Angiotensin System; Tetrazoles; Tyrosine

The purpose of this study was to investigate the efficacy of tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl), a superoxide dismutase mimetic, in preventing early retinal molecular changes in a model that combines hypertension and diabetes.. Four-week-old spontaneously hypertensive rats (SHR) were rendered diabetic by streptozotocin. Diabetic SHR rats (DM-SHR) were randomized to receive or not receive tempol treatment. After 20 days of induction of diabetes, the rats were euthanatized, and their retinas were collected.. The early molecular markers of diabetic retinopathy (DR), glial fibrillary acidic protein, and fibronectin were evaluated by Western blot assays and showed an increase in DM-SHR compared with the SHR group. The oxidative balance, evaluated by superoxide production and nitric oxide end product levels estimated by a nitric oxide analyzer, and the counterpart antioxidative defense revealed an accentuated imbalance in DM-SHR compared with the SHR group. As a result, the product peroxynitrite, which was detected by immunohistochemistry for nitrotyrosine, was higher in the DM-SHR group. The retinal poly-ADP-ribose (PAR)-modified proteins, which reflect the activation of PAR polymerase (PARP), and the inducible nitric oxide synthase (iNOS) expressions were found to have increased in this group. Treatment with tempol reestablished the oxidative parameters and decreased the PAR-modified proteins, thus preventing extracellular matrix accumulation and glial reaction.. The administration of tempol prevented oxidative damage, decreased iNOS levels, and ameliorated the activation of PARP in the retinas of diabetic hypertensive rats. Consequently, the early molecular markers of DR, such as glial reaction (glial fibrillary acidic protein [GFAP]) and extracellular matrix accumulation (fibronectin), were prevented in tempol-treated rats.

Topics: Animals; Blotting, Western; Cyclic N-Oxides; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Fibronectins; Glial Fibrillary Acidic Protein; Glutathione; Hypertension; Immunoenzyme Techniques; Male; Neuroprotective Agents; Nitric Oxide Synthase Type II; Oxidation-Reduction; Oxidative Stress; Peroxynitrous Acid; Poly(ADP-ribose) Polymerases; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Spin Labels; Superoxide Dismutase; Tyrosine

The purpose of this study is to elucidate the effect of wheel training on oxidative stress maker levels in spontaneous hypertensive rats (SHR). 4-hydroxynonenal and 3-nitrotyrosine levels in the aorta of SHRs were allowed to run for 10 weeks from the age of 15 weeks were measured and compared with those of nonexercised SHRs. The 4-hydroxynonenal and 3-nitrotyrosine levels in the exercised group were significantly lower than those in the nonexercised group. The exercised group showed a significant increase of manganese-containing superoxide dismutase. Endurance exercise showed a possible suppressing effect on the arteriosclerosis development by reducing oxidative stress, even after emergence of hypertension.

Topics: Age Factors; Aldehydes; Animals; Aorta; Blood Pressure; Coronary Artery Disease; Fluoroimmunoassay; Hypertension; Motor Activity; Nitric Oxide; Oxidative Stress; Physical Conditioning, Animal; Physical Endurance; Rats; Rats, Inbred SHR; Superoxide Dismutase; Superoxides; Tyrosine

The aim of the study is to investigate the possible mechanism of oxidative stress in the high free fatty acids (FFAs)-induced hypertension. Male Sprague-Dawley rat models were established and classified into three groups, namely the control group (NC group), the FFA group, and the N-acetylcysteine (NAC) group. Blood pressure (BP) was recorded. An organ chamber experiment was performed to determine endothelium-dependent/-independent vasodilation (EDV/EIV). Reactive oxygen species (ROS), nitrotyrosine, reduced glutathione hormone (GSH) and NO(2)(-)/NO(3)(-) levels were measured in plasma. Endothelial nitric oxide synthase (eNOS) mRNA expression in endothelial cells was evaluated by real-time PCR. The following results were observed: (1) In the FFA group, BP increased after 4 h infusion of Intralipid+heparin. In the NAC group, systolic and diastolic BP remained the same. (2) In the FFA group, the aortic rings tended to show impaired EDV in response to acetylcholine (ACh). There was no difference of EDV response in the NAC and NC groups. (3) In the FFA group, NO(2)(-)/NO(3)(-) levels were significantly reduced, and eNOS mRNA expression and activity were significantly decreased compared with the NC group. NAC administration increased eNOS mRNA expression and activity. (4) ROS and nitrotyrosine concentrations in the FFA group were higher than in the NC group, and GSH concentrations in the FFA group were lower than in the NC group. Elevated FFAs can induce elevated BP, potentially through FFA-induced impairment of EDV resulting from decreased eNOS mRNA expression and activity. Oxidative stress may also play an important role in potential mechanisms of this high FFA-induced elevated BP.

Topics: Animals; Blood Pressure; Fatty Acids, Nonesterified; Glucose Clamp Technique; Glutathione; Hypertension; In Vitro Techniques; Male; Nitrates; Nitric Oxide Synthase Type III; Nitrites; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reverse Transcriptase Polymerase Chain Reaction; RNA; Tyrosine

Mechanisms of normalization of blood pressure in spontaneously hypertensive rats (SHR) during pregnancy were investigated. We hypothesized that at the end of pregnancy (20th day), the modified renal renin-angiotensin system (RAS) plays a pivotal role in this effect associated with reduced inflammation and oxidative damage.. We measured blood pressure and heart rate (HR) using a noninvasive tail-cuff method in conscious SHR and Wistar Kyoto rats (WKY). Nonpregnant (-NP) or pregnant (-P) SHR and WKY were used to compare the changes of angiotensin II (ANG II) type 1 (AT1) and type 2 (AT2) receptor expression in the kidney. Renal modification of proinflammatory enzyme expression, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) and their transcription factor nuclear factor-kappaB (NF-kappaB) were also evaluated. Renal malonyldialdehyde (MDA) content and protein nitrotyrosylation, as indicators of oxidative stress, were assessed. Moreover monocyte chemotactic protein-1 (MCP-1) mRNA was determined.. Our findings indicate that the significant reduction of blood pressure induced by pregnancy in the SHR strain could be related to reduced AT1 and increased AT2 expression. We also saw a significant decline in renal NF-kappaB, COX-2, iNOS, and macrophage infiltration, as well as the fall in oxidative stress indicators.. The increased proinflammatory and oxidative variables, seen in SHR, are strongly ameliorated by pregnancy. In pregnant SHR animals, the adaptive and compensative changes of RAS and inflammation in the kidney seem to contribute to the reduction of blood pressure near term.

Topics: Adaptation, Physiological; Animals; Blood Pressure; Chemokine CCL2; Cyclooxygenase 2; Female; Heart Rate; Hypertension; I-kappa B Proteins; Kidney; Lipid Peroxidation; Malondialdehyde; NF-KappaB Inhibitor alpha; Nitric Oxide Synthase Type II; Pregnancy; Pregnancy Complications, Cardiovascular; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Transcription Factor RelA; Tyrosine

In this study we examined the short- and long-term impact of early life dietary sodium (Na) on prenatally programmed hypertension. Hypertension was induced in rat offspring by a maternal low protein (LP) diet. Control and LP offspring were randomized to a high (HS), standard (SS), or low (LS) Na diet after weaning. On the SS diet, the LP pups developed hypertension by 6 weeks of age. The development of hypertension was prevented by the LS diet and exacerbated by the HS diet. Kidney nitrotyrosine content, a measure of oxidative stress, was reduced by the LS diet compared with the HS diet. The modified diets had no effect on control pups. A group of animals on the SS diet was followed up to 51 weeks of age after an early life 3-week exposure to the HS or LS diet. This brief early exposure of LP animals to the LS diet prevented the later development of hypertension and ameliorated the nephrosclerosis observed after early exposure to the HS diet. The LP offspring with early exposure to LS diet had lost their salt-sensitivity when challenged with the HS diet at the age of 43-49 weeks. No effect of early life dietary Na was observed in control animals. These results show that hypertension in this model is salt sensitive and may, in part, be mediated by salt-induced renal oxidative stress and that there may exist a developmental window which allows postnatal "reprogramming" of the hypertension.

Topics: Animals; Blood Pressure; Diet, Protein-Restricted; Female; Hypertension; Kidney; Kidney Glomerulus; Kidney Tubules; Male; Nephrosclerosis; Oxidative Stress; Pregnancy; Prenatal Exposure Delayed Effects; Prenatal Nutritional Physiological Phenomena; Rats; Rats, Sprague-Dawley; Sodium; Tyrosine

The progressive deterioration of renal function and structure resulting from renal mass reduction are mediated by a variety of mechanisms, including oxidative stress and inflammation. Melatonin, the major product of the pineal gland, has potent_antioxidant and anti-inflammatory properties, and its production is impaired in chronic renal failure. We therefore investigated if melatonin treatment would modify the course of chronic renal failure in the remnant kidney model. We studied rats followed 12 wk after renal ablation untreated (Nx group, n = 7) and treated with melatonin administered in the drinking water (10 mg/100 ml) (Nx + MEL group, n = 8). Sham-operated rats (n = 10) were used as controls. Melatonin administration increased 13-15 times the endogenous hormone levels. Rats in the Nx + MEL group had reduced oxidative stress (malondialdehyde levels in plasma and in the remnant kidney as well as nitrotyrosine renal abundance) and renal inflammation (p65 nuclear factor-kappaB-positive renal interstitial cells and infiltration of lymphocytes and macrophages). Collagen, alpha-smooth muscle actin, and transforming growth factor-beta renal abundance were all increased in the remnant kidney of the untreated rats and were reduced significantly by melatonin treatment. Deterioration of renal function (plasma creatinine and proteinuria) and structure (glomerulosclerosis and tubulointerstitial damage) resulting from renal ablation were ameliorated significantly with melatonin treatment. In conclusion, melatonin administration improves the course of chronic renal failure in rats with renal mass reduction. Further studies are necessary to define the potential usefulness of this treatment in other animal models and in patients with chronic renal disease.

Topics: Actins; Animals; Blood Pressure; Cell Movement; Collagen Type IV; Creatinine; Disease Models, Animal; Hypertension; Hypertrophy; Inflammation; Kidney; Kidney Failure, Chronic; Leukocytes; Male; Malondialdehyde; Melatonin; Nephrectomy; Oxidative Stress; Proteinuria; Rats; Rats, Sprague-Dawley; Transcription Factor RelA; Transforming Growth Factor beta; Tyrosine

Coffee is a rich source of antioxidative polyphenols, but epidemiological studies and interventional trials have failed to demonstrate any clear beneficial effects of coffee consumption on hypertension. The interaction between hydroxyhydroquinone (HHQ) and 5-caffeoylquinic acid (CQA) was examined, in an attempt to understand the controversial effects of coffee on hypertension.. Male Wistar Kyoto (WKY) rats or spontaneously hypertensive rats (SHRs, 14 weeks old) were divided into the following four groups; those on a control diet, 0.005% HHQ diet, 0.5% CQA diet, and HHQ plus CQA diet. The rats were fed the above diets for 8 weeks, and the tail arterial blood pressure was monitored in conscious rats at 2-week intervals. Urinary nitric oxide (NO) metabolites and hydrogen peroxide (H(2)O(2)) excretion were measured 8 weeks after the start of the experiment. Endothelium-dependent and -independent vasorelaxant responses and immunohistochemical staining for nitrotyrosine were examined in aortas.. HHQ inhibited the CQA-induced improvement in hypertension, urinary NO metabolites or H(2)O(2) excretion, endothelial dysfunction, and nitrotyrosine deposits in aortas in SHR. However, the administration of HHQ alone had little effect on either strain.. Based on the content ratio of HHQ and chlorogenic acids in coffee, HHQ interfered with the CQA-induced improvement in blood pressure and endothelial function in SHR. The results explain, at least in part, the conflicting action of coffee drinking on hypertension and vascular reactivity.

Topics: Acetylcholine; Animals; Antihypertensive Agents; Blood Pressure; Body Weight; Chlorogenic Acid; Disease Models, Animal; Endothelium, Vascular; Heart Rate; Hydrogen Peroxide; Hydroquinones; Hypertension; Immunohistochemistry; Male; Nitric Oxide; Nitroprusside; Quinic Acid; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Time Factors; Tyrosine; Vasodilation; Vasodilator Agents

The hypertensive rat brain exhibited softening, severe edema and intracerebral hemorrhage. The NO(2) (-) + NO(3) (-) (NOx) level in the hypertensive rat brain was higher than in the normotensive rat brain. Light microscopy demonstrated severe arterial and arteriolar lesions with fibrinoid deposits and medial lesion. After injecting hypertensive rats with nitroblue tetrazolium (NBT), formazan deposits, which are the reaction product of reduction of NBT by superoxide, were observed in the microvessels and nervous tissue around the microvessels of injured brain. Immunohistochemistry showed that copper zinc superoxide dismutase and manganese superoxide dismutase expression of the endothelial cells of hypertensive rats were also upregulated in comparison with normotensive rat endothelial cells. Inducible nitric oxide synthase and endothelial nitric oxide synthase expression in endothelial cells of normotensive rats were strongly positive, whereas the expression in hypertensive rat endothelial cells was weaker. Nitrotyrosine, a biomarker of peroxynitrite, which is a powerful oxidant formed by the reaction of nitric oxide (NO) with superoxide, was found in the microvessels, injured arteries and arterioles and infarcted brain tissue. Deposition of a major aldehydic product of lipid peroxidation, that is, 4-hydroxy-2-nonenal (4-HNE) was found in microvessels, perivascular tissue, and edematous and infarcted brain. Hypertensive cerebrovascular disease is the result of hypertension-induced oxidative stress.

Topics: Aldehydes; Animals; Arterioles; Brain; Brain Edema; Cerebral Hemorrhage; Cerebrovascular Disorders; Disease Models, Animal; Endothelium, Vascular; Hypertension; Intracranial Arterial Diseases; Male; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Nitroblue Tetrazolium; Oxidative Stress; Rats; Rats, Wistar; Superoxide Dismutase; Tyrosine; Up-Regulation

Whether morning blood pressure surge influences the molecular mechanisms of plaque progression toward instability is not known. Recently, we have demonstrated enhanced activity of the ubiquitin-proteasome system in human plaques and evidenced that it is associated with inflammatory-induced plaque rupture. We evaluated the inflammatory infiltration and ubiquitin-proteasome activity in asymptomatic carotid plaques of hypertensive patients with different patterns of morning blood pressure surge. Plaques were obtained from 32 hypertensive patients without morning blood pressure surge and 28 with morning blood pressure surge enlisted to undergo carotid endarterectomy for extracranial high-grade (>70%) internal carotid artery stenosis. Plaques were analyzed for macrophages, T-lymphocytes, human leukocyte antigen-DR+cells, ubiquitin-proteasome activity, nuclear factor-kappaB, inhibitor kB-beta, tumor necrosis factor-alpha, nitrotyrosine, matrix metalloproteinase-9, and collagen content (immunohistochemistry and ELISA). Compared with plaques obtained from hypertensive patients without morning blood pressure surge, plaques from with morning blood pressure surge had more macrophages, T-lymphocytes, human leukocyte antigen-DR+cells (P<0.001), ubiquitin-proteasome activity, tumor necrosis factor-alpha, nuclear factor-kB (P<0.001), nitrotyrosine, and matrix metalloproteinase-9 (P<0.01), along with a lesser collagen content and IkB-beta levels (P<0.001). Enhanced ubiquitin-proteasome activity in atherosclerotic lesions of patients with morning blood pressure surge is associated with inflammatory-dependent unstable plaque phenotype. These data suggest a potential interplay between morning blood pressure surge and ubiquitin-proteasome activity in atherosclerosis pathophysiology.

Topics: Blood Pressure; Blood Pressure Monitoring, Ambulatory; Carotid Artery Diseases; Circadian Rhythm; Humans; Hypertension; In Vitro Techniques; Inflammation; Intracranial Arteriosclerosis; NF-kappa B; Oxidative Stress; Proteasome Endopeptidase Complex; Tyrosine; Ubiquitin; Up-Regulation

The present study was undertaken to identify whether inflammation or oxidative stress is the primary abnormality in the kidney in spontaneously hypertensive rats (SHR). Renal inflammation and oxidative stress were evaluated in 2- and 3-week-old prehypertensive SHR and age-matched genetically normotensive control Wistar-Kyoto (WKY) rats. Blood pressure was similar in WKY and SHR rats at 2 and 3 weeks, of age. Renal inflammation (macrophage and nuclear factor-kappaB) was elevated in SHR at 3 weeks, but not at 2 weeks, of age compared with age-matched WKY rats. Renal oxidative stress (nitrotyrosine, 8-hydroxy-2'-deoxyguanosine and p47phox) was also clearly elevated in 3-week-old SHR compared with age-matched WKY rats. Additionally, NADPH oxidase subunit p47phox was found elevated in 2-week-old SHR compared to age-matched WKY rats. Moreover, antioxidant (N-acetyl-L-cysteine and Tempol) treatment reduced renal inflammation in prehypertensive SHR. We therefore conclude that the oxidative stress appears before inflammation as a primary abnormality in the kidney in prehypertensive SHR.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acetylcysteine; Age Factors; Animals; Antioxidants; Blood Pressure; Cyclic N-Oxides; Deoxyguanosine; Disease Models, Animal; Disease Progression; DNA Damage; Glutathione; Hypertension; Kidney Cortex; Male; NADPH Oxidases; Nephritis; Oxidative Stress; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Spin Labels; Tyrosine

Previous studies have reported that isohumulones, the bitter compounds in beer, improve insulin resistance and hyperlipidemia in several animal models. In this study, we examined whether isohumulones ameliorate renal injury. Dahl salt-sensitive hypertensive rats were fed a low-salt diet (LS), a high-salt diet (HS) or a high-salt diet containing 0.3% isohumulones (HS+IH) for 4 weeks. Urinary nitrite/nitrate (NOx) excretion was measured at 4 weeks along with blood pressure and urinary protein excretion. Renal injury was evaluated histologically and reactive oxygen species (ROS) and nitric oxide (NO) production in the renal cortex was visualized. Oxidative stress and NO synthase (NOS) expression were evaluated by immunohistochemical staining and Western blot analysis. Mean blood pressure was significantly decreased in the HS+IH group compared with the HS group at 4 weeks (158.1+/-8.7 vs. 177.5+/-3.7 mmHg; p<0.05). Isohumulones prevented the development of proteinuria in the HS+IH group compared with the HS group at 2 weeks (61.7+/-26.8 vs. 117.2+/-9.8 mg/day; p<0.05). Glomerulosclerosis and interstitial fibrosis scores were significantly decreased in the HS+IH group compared with the HS group (0.61+/-0.11 vs. 1.55+/-0.23, 23.7+/-6.8 vs. 36.1+/-3.5%; p<0.05 for both). In the HS group, increased ROS and decreased NO were observed in glomeruli in vivo. Isohumulones reduced the ROS production, leading to the restoration of bioavailable NO. Urinary NOx excretion was significantly increased in the HS+IH group compared with the HS group. Furthermore, renal nitrotyrosine was increased in the HS group compared with the LS group, and this effect was prevented by isohumulones. Renal NOS expression did not differ among the three groups. These results suggest that isohumulones may prevent the progression of renal injury caused by hypertension via an anti-oxidative effect.

Topics: Animals; Antioxidants; Blood Pressure; Blotting, Western; Cyclopentanes; Humulus; Hypertension; Kidney Diseases; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitrites; Oxidative Stress; Proteinuria; Rats; Rats, Inbred Dahl; Reactive Oxygen Species; Sodium Chloride; Tyrosine

Progressive renal damage and hypertension are associated with oxidative and nitrosative stress. On the other hand, S-allylcysteine (SAC), the most abundant organosulfur compound in aged garlic extract (AG), has antioxidant properties. The effects of SAC and AG on blood pressure, renal damage, and oxidative and nitrosative stress were studied in five-sixths nephrectomized rats treated with SAC (200 mg/kg ip) and AG (1.2 ml/kg ip) every other day for 30 days. Proteinuria and serum creatinine and blood urea nitrogen concentrations were measured on days 0, 5, 10, 15, and 30, and systolic blood pressure was recorded on days 0, 15, and 30. The degree of glomerulosclerosis and tubulointerstitial damage, the immunostaining for inducible nitric oxide synthase, 3-nitrotyrosine, poly(ADP-ribose), and the subunits of NADPH oxidase p22phox and gp91phox, and the activity of SOD were determined on day 30. SAC and AG reduced hypertension, renal damage, and the abundance of inducible nitric oxide synthase, 3-nitrotyrosine, poly(ADP-ribose), p22phox, and gp91phox and increased SOD activity. Our data suggest that the antihypertensive and renoprotective effects of SAC and AG are associated with their antioxidant properties and that they may be used to ameliorate hypertension and delay the progression of renal damage.

Topics: Animals; Antihypertensive Agents; Antioxidants; Blood Pressure; Blood Urea Nitrogen; Creatinine; Cysteine; Cytoprotection; Garlic; Hypertension; Kidney; Male; Membrane Glycoproteins; NADPH Oxidase 2; NADPH Oxidases; Nephrectomy; Nitric Oxide Synthase Type II; Plant Extracts; Poly Adenosine Diphosphate Ribose; Proteinuria; Rats; Rats, Wistar; Superoxide Dismutase; Systole; Tyrosine

The present study investigates the effects of chronic administration of ACEIs (angiotensin-converting-enzyme inhibitors; either zofenopril or enalapril) in combination with a diruetic (hydrochlorothiazide) on BP (blood pressure) increase and renal injury induced by L-NAME (NG-nitro-L-arginine methyl ester), an inhibitor of NO (nitric oxide) synthesis. Rats were untreated or received L-NAME alone, L-NAME+zofenopril+hydrochlorothiazide or L-NAME+enalapril+hydrochlorothiazide for 8 weeks. L-NAME treatment resulted in marked elevation in BP and mortality. Treatment with either ACEI and diuretic prevented the increase in BP induced by L-NAME, reduced the death rate and improved excretory parameters. Renal injury in the L-NAME group was severe, but, in the groups treated with either ACEI and diuretic, glomerular and tubulointerstitial lesions were not observed and the intensity, number and size of vessels affected was reduced. However, the efficacy of zofenopril+diuretic was superior to that of enalapril+diuretic in reducing vascular alterations. Oxidative stress indices and the expression of NO synthase and nitrotyrosine were normalized by the treatments. In conclusion, the combined treatment of zofenopril or enalapril with hydrochlorothiazide completely prevented the development of arterial hypertension induced by L-NAME. Renal morphological and functional alterations in the hypertensive animals were also almost completely normalized, but the treatment with zofenopril+diuretic produced a more complete organ protection. The protective effect is related to an activation of endothelial NO synthase expression and to a normalization of the oxidative stress parameters due to the inhibition of angiotensin II.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Pressure; Captopril; Diuretics; Drug Therapy, Combination; Enalapril; Hydrochlorothiazide; Hypertension; Kidney; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Oxidative Stress; Rats; Rats, Sprague-Dawley; Tyrosine

Corosolic acid (CRA), a constituent of banaba leaves, has been reported to have anti-inflammatory and hypoglycemic activities. The aim of this study was to determine the effects of CRA on metabolic risk factors including obesity, hypertension, hyperinsulinemia, hyperglycemia, and hyperlipidemia together with oxidative stress and inflammation, all of which are characteristic of the SHR/NDmcr-cp (cp/cp) (SHR-cp) rat, an animal model of metabolic syndrome. Six-week-old male SHR-cp rats were fed a high fat diet containing 0.072% CRA for 14 weeks. Treatment with CRA lowered blood pressure, which was elevated in control animals, by 10% after 8 weeks, and serum free fatty acids by 21% after 2 weeks. CRA treatment resulted in decreases in the levels of the oxidative stress markers thiobarbituric acid-reactive substances and 8-hydroxydeoxyguanosine by 27% and 59%, respectively, after 2 weeks. CRA treatment also reduced the levels of myeloperoxidase markers, 3-nitrotyrosine and 3-chlorotyrosine by 38% and 39%, respectively, after 10 weeks, and tended to decrease the levels of high sensitivity C-reactive protein, a marker of inflammation, after 6 weeks. However, CRA had no effect on weight gain or hyperglycemia. These results demonstrate that CRA can ameliorate hypertension, abnormal lipid metabolism, and oxidative stress as well as the inflammatory state in SHR-cp rats. This implies that CRA can be beneficial for preventing atherosclerosis-related diseases that are an increasing health care problem worldwide.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Blood Glucose; Blood Pressure; Body Weight; Cholesterol; Deoxyguanosine; Disease Models, Animal; Fatty Acids, Nonesterified; Hypertension; Inflammation; Insulin; Male; Metabolic Syndrome; Molecular Structure; Musa; Oxidative Stress; Phytotherapy; Plant Extracts; Rats; Rats, Inbred SHR; Thiobarbituric Acid Reactive Substances; Triglycerides; Triterpenes; Tyrosine

Heme oxygenase (HO) plays a critical role in the regulation of cellular oxidative stress. The effects of the reactive oxygen species scavenger ebselen and the HO inducers cobalt protoporphyrin and stannous chloride (SnCl(2)) on HO protein levels and activity, indices of oxidative stress, and the progression of diabetes were examined in the Zucker rat model of type 2 diabetes. The onset of diabetes coincided with an increase in HO-1 protein levels and a paradoxical decrease in HO activity, which was restored by administration of ebselen. Up-regulation of HO-1 expressed in the early development of diabetes produced a decrease in oxidative/nitrosative stress as manifested by decreased levels of 3-nitrotyrosine, superoxide, and cellular heme content. This was accompanied by a decrease in endothelial cell sloughing and reduced blood pressure. Increased HO activity was also associated with a significant increase in the antiapoptotic signaling molecules Bcl-xl and phosphorylation of p38-mitogen-activated protein kinase but no significant increases in Bcl-2 or BAD proteins. In conclusion, 3-nitrotyrosine, cellular heme, and superoxide, promoters of vascular damage, are reduced by HO-1 induction, thereby preserving vascular integrity and protecting cardiac function involving an increase in antiapoptotic proteins.

Topics: Animals; Antioxidants; Apoptosis; bcl-X Protein; Blood Pressure; Blotting, Western; Diabetic Angiopathies; Endothelial Cells; Heme Oxygenase (Decyclizing); Hypertension; Male; NADPH Oxidases; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Oxygen; Oxygen Consumption; p38 Mitogen-Activated Protein Kinases; Peroxynitrous Acid; Phosphorylation; Rats; Rats, Zucker; Signal Transduction; Tyrosine; Up-Regulation

The present study was carried out to investigate the role of hypertension in the genesis and localization of intimal lesions and medial remodelling found in the prestenotic segment in relation to a severe stenosis of the abdominal aorta just below the diaphragm. Male young rats were divided randomly into operated group, animals submitted to surgical abdominal aorta stenosis, and sham-operated group, a control group of animals submitted to sham operation to simulate abdominal aorta stenosis. Aortas in the hypertensive prestenotic segment with increased circumferential wall tension associated with normal tensile stress, laminar flow/normal wall shear stress were characterized by enlarged heterogeneous endothelial cells elongated in the direction of the blood flow, diffusely distributed conspicuous neointimal plaques and medial thickening. The immunohistochemical analysis revealed an increased expression of eNOS, iNOS, nitrotyrosine and transforming growth factor-beta (TGF-beta) in endothelial cells and/or smooth muscle cells in this segment. Our findings suggest that increased circumferential wall tension due to hypertension plays a pivotal role in the remodelling of the prestenotic segment through biomechanical effects on oxidative stress and increased TGF-beta expression. Further studies are needed to clarify the intrinsic pathogenetic mechanism of focal distribution of the neointimal plaques in the hypertensive segment.

Topics: Animals; Aorta, Abdominal; Aortic Valve Stenosis; Biomarkers; Hypertension; Immunohistochemistry; Male; Microscopy, Electron, Transmission; Models, Animal; Models, Cardiovascular; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Pulsatile Flow; Rats; Rats, Wistar; Stress, Mechanical; Transforming Growth Factor beta; Tunica Intima; Tyrosine; Ultrasonography, Doppler, Color

The present study examined the role of inducible nitric oxide synthase (iNOS) in the rostral ventrolateral medulla (RVLM) of the brain stem, where the vasomotor center is located, in the control of blood pressure and sympathetic nerve activity. Adenovirus vectors encoding iNOS (AdiNOS) or beta-galactosidase (Adbetagal) were transfected into the RVLM in Wistar-Kyoto (WKY) rats. Blood pressure and heart rate were monitored using a radiotelemetry system. iNOS expression in the RVLM was confirmed by immunohistochemical staining or Western blot analysis. Mean arterial pressure significantly increased from day 6 to day 11 after AdiNOS transfection, but did not change after Adbetagal transfection. Urinary norepinephrine excretion was significantly higher in AdiNOS-transfected rats than in Adbetagal-transfected rats. Microinjection of aminoguanidine or S-methylisothiourea, iNOS inhibitors, or tempol, an antioxidant, significantly attenuated the pressor response evoked by iNOS gene transfer. The levels of thiobarbituric acid-reactive substances, a marker of oxidative stress, were significantly greater in AdiNOS-transfected rats than in Adbetagal-transfected rats. Dihydroethidium fluorescence in the RVLM was increased in AdiNOS-transfected rats. In addition, nitrotyrosine-positive cells were observed in the RVLM only in AdiNOS-transfected rats. Intracisternal infusion of tempol significantly attenuated the pressor response and the increase in the levels of thiobarbituric acid-reactive substances induced by AdiNOS transfection. These results suggest that overexpression of iNOS in the RVLM increases blood pressure via activation of the sympathetic nervous system, which is mediated by an increase in oxidative stress.

Topics: Animals; Antioxidants; Blood Pressure; Brain Chemistry; Cattle; Cyclic N-Oxides; Heart Rate; Hypertension; Infusion Pumps, Implantable; Male; Medulla Oblongata; Mice; Microdialysis; Microinjections; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Norepinephrine; Oxidative Stress; Random Allocation; Rats; Rats, Inbred WKY; Recombinant Fusion Proteins; Spin Labels; Superoxides; Sympathetic Nervous System; Transduction, Genetic; Tyrosine; Vasomotor System

The gp91phox-containing NADPH oxidase is the major source of reactive oxygen species (ROS) in the cardiovascular system and inactivation of gp91phox has been reported to blunt hypertension and cardiac hypertrophy seen in angiotensin (Ang) II-infused animals. In the current study, we sought to determine the role of gp91phox-derived ROS on cardiovascular outcomes of chronic exposure to Ang II. The gp91phox-deficient mice were crossed with transgenic mice expressing active human renin in the liver (TTRhRen). TTRhRen mice exhibit chronic Ang II-dependent hypertension and frank cardiac hypertrophy by age 10 to 12 weeks. Four genotypes of mice were generated: control, TTRhRen trangenics (TTRhRen), gp91phox-deficient (gp91-), and TTRhRen transgenic gp91phox-deficient (TTRhRen/gp91-). Eight to 10 mice/group were studied. ROS levels were significantly reduced (P<0.05) in the heart and aorta of TTRhRen/gp91- and gp91-mice compared with control counterparts, and this was associated with reduced cardiac, aortic, and renal NADPH oxidase activity (P<0.05). Systolic blood pressure (SBP), cardiac mass, and cardiac fibrosis were increased in TTRhRen versus controls. In contrast to its action on ROS generation, gp91phox inactivation had no effect on development of hypertension or cardiac hypertrophy in TTRhRen mice, although interstitial fibrosis was reduced. Cardiac and renal expression of gp91phox homologues, Nox1 and Nox4, was not different between groups. Thus, although eliminating gp91phox-associated ROS production may be important in cardiovascular consequences in acute insult models, it does not prevent the development of hypertension and cardiac hypertrophy in a model in which the endogenous renin-angiotensin system is chronically upregulated.

Topics: Angiotensin II; Animals; Blood Pressure; Cardiomegaly; Chronic Disease; Collagen; Humans; Hypertension; Kidney; Membrane Glycoproteins; Mice; Mice, Transgenic; Myocardium; NADH, NADPH Oxidoreductases; NADPH Oxidase 1; NADPH Oxidase 2; NADPH Oxidase 4; NADPH Oxidases; Reactive Oxygen Species; Renin; Tyrosine

Spontaneously hypertensive rats (SHR) have a higher level of oxidative stress and exhibit a greater depressor response to a superoxide scavenger, tempol, than normotensive Wistar-Kyoto rats (WKY). This study determined whether an increase in oxidative stress with a superoxide/NO donor, molsidomine, would amplify the blood pressure in SHR. Male SHR and WKY were given molsidomine (30 mg.kg(-1).day(-1)) or vehicle (0.01% ethanol) for 1 wk, and blood pressure, renal hemodynamics, nitrate and nitrite excretion (NOx), renal superoxide production, and expression of renal antioxidant enzymes, Mn- and Cu,Zn-SOD, catalase, and glutathione peroxidase (GPx), were measured. Renal superoxide and NOx were higher in control SHR than in WKY. Molsidomine increased superoxide by approximately 35% and NOx by 250% in both SHR and WKY. Mean arterial blood pressure (MAP) was also higher in control SHR than WKY. Molsidomine increased MAP by 14% and caused renal vasoconstriction in SHR but reduced MAP by 16%, with no effect on renal hemodynamics, in WKY. Renal expression of Mn- and Cu,Zn-SOD was not different between SHR and WKY, but expression of catalase and GPx were approximately 30% lower in kidney of SHR than WKY. The levels of Mn- and Cu,Zn-SOD were not increased with molsidomine in either WKY or SHR. Renal catalase and GPx expression was increased by 300-400% with molsidomine in WKY, but there was no effect in SHR. Increasing oxidative stress elevated blood pressure further in SHR but not WKY. WKY are likely protected because of higher bioavailable levels of NO and the ability to upregulate catalase and GPx.

Topics: Animals; Blood Pressure; Hemodynamics; Hypertension; Kidney; Male; Molsidomine; Nitrates; Nitric Oxide Donors; Nitrites; Oxidative Stress; Oxidoreductases; Proteins; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Renal Circulation; Superoxides; Tyrosine

Recent studies suggest that adipose tissue hormone, leptin, is involved in the pathogenesis of arterial hypertension. However, the mechanism of hypertensive effect of leptin is incompletely understood. We investigated whether antioxidant treatment could prevent leptin-induced hypertension. Hyperleptinemia was induced in male Wistar rats by administration of exogenous leptin (0.25 mg/kg twice daily s.c. for 7 days) and separate groups were simultaneously treated with superoxide scavenger, tempol, or NAD(P)H oxidase inhibitor, apocynin (2 mM in the drinking water). After 7 days, systolic blood pressure was 20.6% higher in leptin-treated than in control animals. Both tempol and apocynin prevented leptin-induced increase in blood pressure. Plasma concentration and urinary excretion of 8-isoprostanes increased in leptin-treated rats by 66.9% and 67.7%, respectively. The level of lipid peroxidation products, malonyldialdehyde + 4-hydroxyalkenals (MDA+4-HNE), was 60.3% higher in the renal cortex and 48.1% higher in the renal medulla of leptin-treated animals. Aconitase activity decreased in these regions of the kidney following leptin administration by 44.8% and 45.1%, respectively. Leptin increased nitrotyrosine concentration in plasma and renal tissue. Urinary excretion of nitric oxide metabolites (NO(x)) was 57.4% lower and cyclic GMP excretion was 32.0% lower in leptin-treated than in control group. Leptin decreased absolute and fractional sodium excretion by 44.5% and 44.7%, respectively. Co-treatment with either tempol or apocynin normalized 8-isoprostanes, MDA+4-HNE, aconitase activity, nitrotyrosine, as well as urinary excretion of NO(x), cGMP and sodium in rats receiving leptin. These results indicate that oxidative stress-induced NO deficiency is involved in the pathogenesis of leptin-induced hypertension.

Topics: Acetophenones; Aconitate Hydratase; Aldehydes; Animals; Antioxidants; Blood Pressure; Body Weight; Creatine; Cyclic GMP; Cyclic N-Oxides; Drinking; Eating; Hypertension; Isoprostanes; Kidney; Leptin; Male; Malondialdehyde; Natriuresis; Nitric Oxide; Rats; Rats, Wistar; Reactive Nitrogen Species; Sodium; Spin Labels; Tyrosine

Topics: Angiotensin II; Animals; Antioxidants; Biopterins; Cardiomegaly; Endothelium, Vascular; Hypertension; Immunohistochemistry; Male; Myocardium; NADPH Oxidases; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Rats; Rats, Sprague-Dawley; RNA, Messenger; Superoxides; Tyrosine; Up-Regulation

The pteridine cofactor tetrahydrobiopterin (BH4) has emerged as a critical determinant of endothelial nitric oxide synthase (eNOS) activity. When BH4 availability is limited, eNOS does not produce nitric oxide (NO) but instead generates superoxide. BH4 may reverse endothelial dysfunction due to cardiovascular disease, including atherosclerosis, coronary artery disease and hypertension. In this study, the influence of BH4 on cardiovascular parameters and the production of free radicals following angiotensin II (Ang II) infusion was assessed.. BH4 (20 mg/kg per day in drinking water) was administered with Ang II (300 ng/kg per min subcutaneously, osmotic pump) for 7 days in Sprague-Dawley rats. In addition, BH4 was also given in vehicle-infused rats.. Treatment with BH4 significantly prevented some of the effects of Ang II, such as impaired vascular responses to acetylcholine, hypertension and increases in heart weight index values. Treatment with BH4 also significantly reduced Ang II-induced increases in inducible NO synthase expression, nitrotyrosine immunostaining, NO production and superoxide anion formation in rats.. These results indicate that BH4 might prevent the development of hypertension and myocardial hypertrophy, as well as the Ang II-induced production of superoxide and NO, thereby reducing the production of peroxynitrite. Therefore, BH4 may protect against the cardiovascular manifestations of oxidative and nitrosative stress in this experimental model of Ang II-mediated hypertension.

Topics: Acetophenones; Angiotensin II; Animals; Antioxidants; Aorta, Thoracic; Biopterins; Cardiomegaly; Disease Models, Animal; Enzyme Inhibitors; Hypertension; Immunohistochemistry; Male; NADPH Oxidases; Nitrates; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Nitrites; Oxidative Stress; Rats; Rats, Sprague-Dawley; RNA, Messenger; Superoxides; Time Factors; Tyrosine; Up-Regulation

Although NO derived from endothelial NO synthase (eNOS) is thought to be cardioprotective, the role of inducible NO synthase (iNOS) remains controversial. Using mice lacking iNOS (iNOS-/-), we studied (1) whether development of hypertension, cardiac hypertrophy, and dysfunction after deoxycorticosterone acetate (DOCA)-salt would be less severe compared with wild-type controls (WT; C57BL/6J), and (2) whether the cardioprotection attributable to lack of iNOS is mediated by reduced oxidative stress. Mice were uninephrectomized and received either DOCA-salt (30 mg/mouse SC and 1% NaCl+0.2% KCl in drinking water) or vehicle (tap water) for 12 weeks. Systolic blood pressure (SBP) was measured weekly. Left ventricular (LV) ejection fraction (EF) by echocardiography and cardiac response to isoproterenol (50 ng/mouse IV) were studied at the end of the experiment. Expression of eNOS and iNOS as well as the oxidative stress markers 4-hydroxy-2-nonenal (4-HNE, a marker of lipid peroxidation) and nitrotyrosine (a marker for peroxynitrite) were determined by Western blot and immunohistochemical staining, respectively. DOCA-salt increased SBP and LV weight similarly in both strains and decreased EF in WT but not in iNOS-/-. Cardiac contractile and relaxation responses to isoproterenol were greater, 4-HNE and nitrotyrosine levels were lower, and eNOS expression tended to be higher in iNOS-/-. We conclude that lack of iNOS leads to better preservation of cardiac function, which may be mediated by reduced oxidative stress and increased eNOS; however, it does not seem to play a significant role in preventing DOCA-salt-induced hypertension and hypertrophy.

Topics: Aldehydes; Animals; Blood Pressure; Cardiotonic Agents; Desoxycorticosterone; Heart; Hypertension; Hypertrophy, Left Ventricular; Isoproterenol; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardium; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Oxidative Stress; Sodium Chloride; Tyrosine

Superoxide is increased in the vessel wall of spontaneously hypertensive rats (SHR) where, if "blocked," potentiates endothelium-dependent vasodilation. The purpose of this study was to determine the role of superoxide anion in hypertension and its interaction with nitric oxide (NO). For this purpose we used a low molecular weight synthetic superoxide dismutase mimetic (M40403), known to remove selectively superoxide anion. Baseline mean arterial pressure (MAP) was significantly elevated in the SHR compared with its normal counterpart, Wistar Kyoto (WKY). M40403 at a dose (2 mg x kg(-1) x h(-1)), which had no effect in the WKY, significantly decreased MAP in SHR rats. To determine whether superoxide anion increases MAP by inactivating NO, NO synthesis was blocked with N(G) nitro-arginine methyl ester (L-NAME, 3 mg/kg i.v.), a nonselective nitric oxide synthase inhibitor. L-NAME (3 mg/kg, i.v) blocked the anti-hypertensive effect of M40403 (2 mg/kg over 30 min). When used at a dose that yielded similar increases in MAP, norepinephrine (2.1 microg/kg) failed to alter the anti-hypertensive effects of M40403 in the SHR. To investigate whether the anti-hypertensive effect of M40403 was associated with an improvement of the alterations in vascular reactivity, a separate group of experiments was carried out ex vivo. Endothelium-dependent vasorelaxation to acetylcholine (10 nM-10 microM), an index of endothelial function, was reduced in aortic rings taken from SHR rats when compared with WKY rats. In vivo treatment with M40403 caused an improvement of the degree of the endothelial dysfunction in SHR rats. Furthermore, immunohistochemical analysis for nitrotyrosine (the product formed from the interaction of nitric oxide with superoxide) revealed a positive staining in aorta from SHR rats. The degree of staining for nitrotyrosine was markedly reduced in tissue sections obtained from SHR rats treated with M40403. Our data suggest that overt production of superoxide in SHR couples with nitric oxide, reducing its function and leading to a loss of blood vessel tone and hypertension. Another important effect appears to be at the level of endothelial cellular integrity, where by interacting with nitric oxide, superoxide anion forms peroxynitrite and subsequent endothelial cell dysfunction. By removing superoxide, M40403 restores blood pressure to near-to-normal values.

Topics: Animals; Aorta; Blood Pressure; Culture Techniques; Hypertension; Kinetics; Manganese; Organometallic Compounds; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Superoxides; Tyrosine; Vasodilation

1. The roles of nitric oxide (NO), superoxide anion (O(2)(-)), and hydrogen peroxide (H(2)O(2)) in the modulation of spontaneous tone were investigated in isolated aorta from deoxycorticosterone acetate (DOCA)-salt hypertensive rats. 2. Increases in preload from 1 to 5 g were accompanied by increases in spontaneous tone in aortic rings from DOCA-salt hypertensive rats but not from SHAM-normotensive rats. 3. Tone was higher in endothelium-denuded aortic rings than in endothelium-intact vessels. Inhibition of nitric oxide synthase (NOS) with 300 microM N(G)-nitro-L-arginine methyl ester (l-NAME) increased spontaneous tone. 4. Basal O(2)(-) generation was higher in aortic rings from DOCA-salt hypertensive rats than in those from SHAM-normotensive rats. Stretch increased O(2)(-) levels even further in the DOCA-salt group. In rings isolated from DOCA-salt hypertensive rats, administration of the O(2)(-) scavenger, superoxide dismutase (SOD, 150 U ml(-1)), or the nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase inhibitor, apocynin (100 microM), completely abolished the development of spontaneous tone in endothelium-intact aortic rings but not in endothelium-denuded or in L-NAME-treated rings. SOD and apocynin decreased the generation of O(2)(-) in endothelium-intact, endothelium-denuded, and L-NAME-treated aortic rings. 5. Oral treatment of DOCA-salt hypertensive rats with the O(2)(-) scavengers, tempol or tiron, or with apocynin for 3 weeks prevented the development of hypertension and abolished the increases in O(2)(-) generation and spontaneous tone. 6. Administration of catalase (1000 U ml(-1)) to aortic rings increased spontaneous tone in vessels from DOCA-salt hypertensive rats. 7. Administration of the cyclooxygenase (COX) inhibitor, valeroyl salicylate, or the thromboxane/prostaglandin antagonist, SQ 29548, to aortic rings abolished tone. 8. The results suggest that NO plays a major role in preventing the generation of spontaneous tone in isolated aortic rings from DOCA-salt hypertensive rats. NADPH-oxidase-derived O(2)(-) enhanced spontaneous tone by inactivating NO. Endogenous H(2)O(2) appears to mitigate the increase in tone. In addition, a COX component may also contribute to spontaneous tone.

Topics: Acridines; Animals; Aorta, Thoracic; Blood Pressure; Blotting, Western; Calcium; Catalase; Cyclooxygenase Inhibitors; Desoxycorticosterone; Endothelium, Vascular; Hydrogen Peroxide; Hypertension; Immunohistochemistry; In Vitro Techniques; Luminescent Measurements; Male; Muscle Contraction; Muscle Tonus; Muscle, Smooth, Vascular; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Oligopeptides; Oxidative Stress; Oxygen; Peptides, Cyclic; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Thromboxane; Superoxides; Tyrosine; Xanthine Oxidase

Phytoestrogens are considered to be natural selective estrogen receptor modulators exerting antioxidant activity and improving vascular function. However, the mechanisms responsible for their antioxidative effects remain largely unknown. This study tested the hypothesis that genistein may provide significant endothelial protection by antioxidative effects through attenuating NADPH oxidase expression and activity. The results showed that genistein suppressed the expressions of the p22phox NADPH oxidase subunit and angiotensin II (Ang II) type 1 (AT1) receptor in a concentration- and time-dependent manner in aortic endothelial cells from stroke-prone spontaneously hypertensive rats examined by Western blot analysis. Treatment with genistein also remarkably reduced the Ang II-induced superoxide by the reduction of nitroblue tetrazolium, inhibited nitrotyrosine formation, and attenuated endothelin-1 production by ELISA via the stimulation of Ang II. However, when cells were pretreated with ICI-182780, an estrogen-receptor antagonist, at a concentration of 50 micromol/l for 30 min and then co-incubated with ICI-182780 and genistein for 24 h, the inhibitory effect of genistein was not blocked. In contrast, the inhibitory effect of genistein treatment was partially reversed by 30-min pretreatment of endothelial cells with GW9662, a peroxisome proliferator-activated receptor gamma (PPARgamma) antagonist. Genistein thus appears to act as an antioxidant at the transcription level by the downregulation of p22phox and AT1 receptor expression. Our data also showed that the PPARgamma pathway was involved, at least in part, in the inhibitory effect of genistein on the expression of p22phox and AT1 receptors. The endothelial-protective effects of phytoestrogen may contribute to improvement of cardiovascular functions.

Topics: Angiotensin II; Anilides; Animals; Aorta, Thoracic; Cells, Cultured; Endothelin-1; Endothelium, Vascular; Enzyme Inhibitors; Estradiol; Estrogen Antagonists; Fulvestrant; Genistein; Hypertension; Male; Membrane Transport Proteins; NADPH Dehydrogenase; NADPH Oxidases; Phosphoproteins; PPAR gamma; Rats; Rats, Inbred SHR; Receptor, Angiotensin, Type 1; Signal Transduction; Stroke; Superoxides; Tyrosine; Vasoconstrictor Agents

Development and progression of end-organ damage in hypertension have been associated with increased oxidative stress. Superoxide anion accumulation has been reported in deoxycorticosterone acetate (DOCA)-salt hypertension, in which endothelin-1 plays an important role in cardiovascular damage. We hypothesized that blockade of ETA receptors in DOCA-salt rats would decrease oxidative stress. Both systolic blood pressure (SBP, 210+/-9 mm Hg; P<0.05) and vascular superoxide generation in vivo were increased in DOCA-salt (44.9+/-10.3% of ethidium bromide-positive nuclei; P<0.05) versus control uninephrectomized (UniNx) rats (118+/-3 mm Hg; 18.5+/-3%, respectively). In DOCA-salt rats, the ETA antagonist BMS 182874 (40 mg/kg per day PO) lowered SBP (170+/-4 versus UniNx, 120+/-3 mm Hg) and normalized superoxide production (21.7+/-6 versus UniNx, 11.9+/-7%). Vitamin E (200 mg/kg per day PO) decreased superoxide formation in DOCA-salt rats (18.8+/-7%) but did not alter SBP. Oxidative stress in nonstimulated circulating polymorphonuclear cells (PMNs) or in PMNs treated with zymosan, an inducer of superoxide release, was similar in DOCA-salt and UniNx groups. Superoxide formation by PMNs was unaffected by treatment with BMS 182874. Western blot analysis showed increased nitrotyrosine-containing proteins in mesenteric vessels from DOCA-salt compared with UniNX. Treatment with either BMS 182874 or vitamin E abolished the differences in vascular nitrotyrosine-containing proteins between DOCA-salt and UniNX. Maximal relaxation to acetylcholine was decreased in DOCA-salt aortas (75.8+/-4.2% versus UniNx, 95.4+/-1.9%, P<0.05). BMS 182874 treatment increased acetylcholine-induced relaxation in DOCA-salt aortas to 93.5+/-4.5%. These in vivo findings indicate that increased vascular superoxide production is associated with activation of the endothelin system through ETA receptors in DOCA-salt hypertension, in apparently blood pressure-independent fashion.

Topics: Acetylcholine; Animals; Aorta; Arterioles; Blood Pressure; Culture Techniques; Dansyl Compounds; Desoxycorticosterone; Endothelin Receptor Antagonists; Hypertension; Male; Neutrophils; Oxidative Stress; Proteins; Rats; Rats, Wistar; Receptor, Endothelin A; Sodium Chloride; Superoxides; Tyrosine; Vasodilation; Vasodilator Agents

Reactive oxygen species are produced during exercise. The antioxidants prevent or limit tissue damages by these species in physiological conditions. In particular, ascorbate and urate scavenge peroxynitrite, which can alter the function of many molecules, including the lecithin-cholesterol acyltransferase (LCAT) enzyme involved in reverse cholesterol transport. The aims of the present study were to compare the plasma antioxidant response to an ergometric test (ET) in hypertensive and healthy subjects, evaluate the exercise-dependent nitrosative stress in plasma, and assess whether the LCAT activity is altered by the exercise. Plasma samples, prepared before and after ET from hypertensive or healthy volunteers, were analysed for their levels of ascorbate, urate, alpha-tocopherol, retinol, nitrotyrosine, and LCAT activity. The alpha-tocopherol and retinol levels did not significantly change in both groups during exercise, while the ascorbate level changed displaying higher increase in controls (+38.8%) than in hypertensives (+17.2%). In these patients, during ET, the urate and nitrotyrosine levels changed more than in normotensives (+13.5 and +40.6% vs -3.1 and +25.2%, respectively). The antioxidants effectively prevented loss or reduction of LCAT activity, as it was similar in hypertensives and normotensives, and did not change after ET. The results demonstrate that exercise is associated with enhanced protein nitrosation, and suggest that the ascorbate or urate levels increase to limit oxidative damage.

Topics: Adult; Aged; Antioxidants; Exercise; Exercise Test; Female; Humans; Hypertension; Male; Middle Aged; Phosphatidylcholine-Sterol O-Acyltransferase; Reference Values; Time Factors; Tyrosine

Topics: Animals; Blood Pressure; Endothelium, Vascular; Humans; Hypertension; Kidney; Neurons; Nitric Oxide; Nitric Oxide Synthase; Tissue Distribution; Tyrosine

To study the cellular distribution and the expression of the major isoforms of NO synthase (NOS) and of nitrotyrosine in the kidney in spontaneous hypertension.. We have studied by immunohistochemistry the location of the endothelial (eNOS), neuronal (nNOS) and inducible (iNOS) isoforms and nitrotyrosine in kidney slices from normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) using specific antibodies. In order to quantify the expression of these proteins, we have analyzed dissected renal cortical and medullary sections by means of Western blot.. Tubular cells were immunoreactive to nNOS and more numerous in the renal medulla of the SHR compared with that of the WKY, specifically in the outer medulla and the papillary region. Western blot also showed higher expression of nNOS in the renal medulla, but not the renal cortex of the SHR. In contrast, iNOS and eNOS distribution and expression were similar in the kidneys of WKY rats and SHR. Immunohistochemistry showed immunoreactive cells to nitrotyrosine in a variety of renal cells similarly distributed in SHR and WKY kidneys. Western analysis detected three proteins of 14.5, 23.7 and 39 kDa immunoreactive to nitrotyrosine, showing a higher expression in the renal cortex compared to the renal medulla.. The expression of nNOS is higher in the renal medulla of the SHR, and the distribution of eNOS, iNOS and nitrotyrosine is similar in SHR and WKY rats. It is proposed that the higher expression of the neuronal isoform in the medullary tubular cells is a protective mechanism aimed to improve renal function in spontaneous hypertension.

Topics: Animals; Blood Pressure; Blotting, Western; Disease Models, Animal; Endothelium, Vascular; Hypertension; Immunohistochemistry; Kidney; Male; Models, Cardiovascular; Neurons; Nitric Oxide Synthase; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Tissue Distribution; Tyrosine

Atherosclerotic renovascular disease may augment deterioration of renal function and ischemic nephropathy compared with other causes of renal artery stenosis (RAS), but the underlying mechanisms remain unclear. This study was designed to test the hypothesis that concurrent early atherosclerosis and hypoperfusion might have greater early deleterious effects on the function and structure of the stenotic kidney.. Regional renal hemodynamics and function at baseline and during vasoactive challenge (acetylcholine or sodium nitroprusside) were quantified in vivo in pigs by electron-beam computed tomography after a 12-week normal (n=7) or hypercholesterolemic (HC, n=7) diet, RAS (n=6), or concurrent HC and a similar degree of RAS (HC+RAS, n=7). Flash-frozen renal tissue was studied ex vivo. Basal cortical perfusion and single-kidney glomerular filtration rate (GFR) were decreased similarly in the stenotic RAS and HC+RAS kidneys, but tubular fluid reabsorption was markedly impaired only in HC+RAS. Perfusion responses to challenge were similarly blunted in the experimental groups. Stimulated GFR increased in normal, HC, and RAS (38.3+/-3.6%, 36.4+/-7.6%, and 60.4+/-9.3%, respectively, P<0.05), but not in HC+RAS (6.5+/-15.1%). These functional abnormalities in HC+RAS were accompanied by augmented perivascular, tubulointerstitial, and glomerular fibrosclerosis, inflammation, systemic and tissue oxidative stress, and tubular expression of nuclear factor-kappaB and inducible nitric oxide synthase.. Early chronic HC+RAS imposes distinct detrimental effects on renal function and structure in vivo and in vitro, evident primarily in the tubular and glomerular compartments. Increased oxidative stress may be involved in the proinflammatory and progrowth changes observed in the stenotic HC+RAS kidney, which might potentially facilitate the clinically observed progression to end-stage renal disease.

Topics: Animals; Antioxidants; Arteriosclerosis; Cholesterol, Dietary; Disease Models, Animal; Disease Progression; Glomerular Filtration Rate; Hemodynamics; Hypercholesterolemia; Hypertension; Immunohistochemistry; Kidney; Kidney Function Tests; Kidney Tubules; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Oxidation-Reduction; Regional Blood Flow; Renal Artery Obstruction; Swine; Tomography, X-Ray Computed; Tyrosine; Vasodilator Agents

Induction of chronic oxidative stress by glutathione (GSH) depletion has been shown to cause hypertension in normal rats. This was accompanied by and perhaps in part due to inactivation and sequestration of NO by reactive oxygen species (ROS), leading to diminished NO bioavailability. This study was designed to examine renal histology, nitric oxide synthase (NOS) isotype expression, and nitrotyrosine distribution in this model. Sprague-Dawley rats were subjected to oxidative stress by administration of the GSH synthase inhibitor buthionine sulfoximine (BSO; 30 mM/l in drinking water) for 2 weeks. The controls were given tap water. Blood pressure, renal histology, tissue expression of endothelial and inducible NOS (eNOS and iNOS) and nitrotyrosine, tissue GSH content, and urinary excretion of NO metabolites (NOx) were examined. The BSO-treated group showed a 3-fold decrease in tissue GSH content, a marked elevation in blood pressure, and a significant reduction in the urinary excretion of NOx. Histological examination of kidneys revealed no significant abnormalities in either group. In addition, no significant differences were observed in either intensities or localizations of eNOS and iNOS in the kidney. However, the BSO-treated group exhibited intense accumulation in the renal tissue of nitrotyrosine, which is the footprint of NO oxidation by ROS. These observations suggest that oxidative stress-induced hypertension is not caused by either structural abnormality of or depressed NOS expression by the kidney in this model. Instead, it is associated with and perhaps partially related to enhanced renal NO inactivation by ROS and diminished NO bioavailability.

Topics: Animals; Arginine; Blood Pressure; Gene Expression Regulation, Enzymologic; Glutathione Synthase; Hypertension; Immunoenzyme Techniques; Kidney; Male; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Oxidative Stress; Rats; Rats, Sprague-Dawley; Tyrosine

Several recent studies have demonstrated that various forms of hypertension are associated with enhanced reactive oxygen species (ROS) activity. We have recently shown that long-term consumption of a diet similar to that ingested in westernized societies, containing high saturated fat and refined carbohydrate, induces oxidative stress and hypertension in normal rats. We hypothesized that diet modification may reverse diet-induced hypertension via (among other mechanisms) decreased ROS activity and improved nitric oxide (NO) availability. To test this hypothesis, female Fischer rats were placed on either a high-fat (primarily saturated), refined carbohydrate (sucrose) diet (HFS) or low-fat, complex-carbohydrate diet (LFCC) starting at 2 months of age. After 2 years when hypertension was well established, a group of HFS rats was converted to the LFCC diet (HFS/LFCC group) for a period of 2 months. Plasma malondialdehyde, a marker of lipid peroxidation by ROS, was elevated in the HFS group. Hypertension was present in the HFS group at 2 years as was a significant accumulation, in various tissues, of nitrotyrosine, which is the footprint of NO inactivation by ROS. Conversion from the HFS to the LFCC diet for 2 months led to normalization of blood pressure and reduced nitrotyrosine accumulation in the absence of caloric restriction. These results demonstrate that oxidative stress and hypertension induced by long-term consumption of an HFS diet are reversible with implementation of a low-fat, unrefined carbohydrate diet. The effects of the HFS diet and subsequent conversion to the LFCC diet on blood pressure appear to be, in part, mediated by changes in NO availability.

Topics: Animals; Dietary Carbohydrates; Dietary Fats; Female; Hypertension; Nitric Oxide; Oxidative Stress; Rats; Rats, Inbred F344; Reactive Oxygen Species; Time Factors; Tyrosine

Lead-induced hypertension has previously been shown to be closely associated with an increase in reactive oxygen species in low lead (100 ppm)-treated rats. The present study has attempted to define the specific moiety involved by noting the blood pressure (BP), reactive oxygen species (MDA-TBA), hydroxyl radical, and nitrotyrosine responses to infusion of the reactive oxygen species scavenger dimethylthiourea. Dimethylthiourea, a reputed scavenger of hydroxyl radical, normalized BP and MDA-TBA in the lead-treated rats but had no effect in normal control animals. MDA-TBA, hydroxyl radical, and nitrotyrosine, the tissue end product of peroxynitrite, were reduced to or toward normal by dimethylthiourea. The results, therefore, are consistent with the suggestion that either hydroxyl radical or peroxynitrite may be the reactive species affected by lead.

Topics: Animals; Blood Pressure; Free Radical Scavengers; Hydroxyl Radical; Hypertension; Lead; Lipid Peroxides; Male; Rats; Rats, Sprague-Dawley; Thiourea; Tyrosine

Abdominal aortic coarctation above the renal arteries leads to severe hypertension (HTN) above the stenotic site. We have recently shown marked up-regulations of endothelial nitric oxide synthase (eNOS) in heart and thoracic aorta and of neuronal NOS (nNOS) in the brain of rats with severe aortic coarctation above the renal arteries. We hypothesize that the presence of severe regional HTN in the face of marked up-regulation of NO system may be partly due to enhanced NO inactivation by reactive oxygen species (ROS) leading to functional NO deficiency.. Tissue nitrotyrosine (which is the footprint of NO interaction with ROS) was determined by Western blot in sham-operated control and aortic-banded (above renal arteries) rats three weeks postoperatively. Intra-arterial pressure and tissue nitrotyrosine (Western blot) were measured.. The banded group showed a marked rise in arterial pressure measured directly through a carotid cannula (203 +/- 9 vs. 131 +/- 2 mm Hg, P < 0.01). Compared with the sham-operated controls, the banded animals exhibited significant increases in nitrotyrosine abundance in the heart, brain, and the aorta segment above the stricture. In contrast, nitrotyrosine abundance was unchanged in the abdominal aorta segment below the stricture wherein blood pressure was not elevated.. Coarctation-induced HTN is associated with increased nitrotyrosine abundance in all tissues exposed to high arterial pressure, denoting enhanced ROS-mediated inactivation and sequestration of NO in these sites. This can, in part, account for severe regional HTN in this model. The normality of nitrotyrosine abundance in the abdominal aorta wherein blood pressure is not elevated points to the role of baromechanical factors as opposed to circulating humoral factors that were necessarily similar in both segments.

Topics: Animals; Aorta, Abdominal; Aorta, Thoracic; Aortic Coarctation; Baroreflex; Blotting, Western; Brain; Disease Models, Animal; Hypertension; Male; Myocardium; Nitric Oxide; Oxidative Stress; Rats; Rats, Sprague-Dawley; Tyrosine

The spontaneously hypertensive rat (SHR) has enhanced tubuloglomerular feedback (TGF) responses and diminished buffering by juxtaglomerular apparatus (JGA)-derived nitric oxide (NO) despite enhanced expression of NO synthase (NOS) isoforms in the JGA. We tested the hypothesis that the enhanced TGF response is due to inactivation of NO by oxygen radicals (O(-)(2)). SHR had significantly (P<0.05) greater expression of the peroxynitrate reaction product, nitrotyrosine, in renal cortex. A membrane-permeant, metal-independent superoxide dismutase mimetic, tempol, was used to test the functional role of O(-)(2). Maximum TGF responses, assessed from changes in proximal stop-flow pressure (P(SF)) during orthograde loop of Henle (LH) perfusion of artificial tubular fluid (ATF), were enhanced in SHR [Wistar-Kyoto rat (WKY) 8.8+/-0.4 (n = 30 nephrons) vs. SHR 10.8+/-0.4 mm Hg (n = 39 nephrons), P<0.001]. TGF responses of SHR were unresponsive to microperfusion of 7-nitroindazole (7-NI, 10(-4) M), which is an inhibitor of neuronal NOS (nNOS) [WKY 8.3+/-0.3 to 10.8+/-0.4 (n = 8, P<0.001) vs. SHR 10.0+/-0.7 to 10.5+/-0.8 mm Hg (n = 8; not significant)]. Microperfusion of tempol (10(-4) M) into the efferent arteriole (EA) supplying the peritubular capillaries (PTC) blunted TGF. The response to tempol was significantly (P< 0.05) greater in SHR [DeltaTGF in WKY 19+/-6% (n = 10) vs. SHR 32+/-3% (n = 10)]. Microperfusion of the NO donor compound S-nitroso-N-acetyl-penicillamine (SNAP, 10(-7)-10(-4) M) via the LH blunted TGF, but the sensitivity of the response was impaired significantly (P<0.05) in SHR nephrons. PTC perfusion of tempol (10(-4) M) normalized the response to loop perfusion of both SNAP and 7-NI in SHR nephron to levels in WKY (during tempol, DeltaP(SF) with 7-NI in WKY 8.9+/-0.6 to 11.4+/-0.8; n = 12 vs. SHR 9.5+/-0.5 to 12.5+/-0.4 mm Hg; n = 16). In conclusion, TGF responses are enhanced in SHR, in part due to a diminished role for NO from nNOS in blunting TGF due to enhanced O(-)(2) formation. O(-)(2) in the JGA enhances TGF responses by inactivation of locally generated NO.

Topics: Animals; Cyclic N-Oxides; Feedback; Hypertension; Indazoles; Kidney Glomerulus; Kidney Tubules; Male; Nitric Oxide; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Spin Labels; Superoxide Dismutase; Superoxides; Tyrosine

We have recently demonstrated that long-term consumption of a high-fat, refined-carbohydrate (HFS) diet induces hypertension (HTN) in normal rats compared with a low-fat, complex-carbohydrate (LFCC) diet. Limited evidence suggests that high-fat or high-sugar diets cause enhanced generation of reactive oxygen species (ROS). We therefore hypothesized that by inducing oxidative stress, the HFS diet may promote nitric oxide (NO) inactivation and HTN. To test this hypothesis, female Fischer rats were placed on either the HFS or the LFCC diet starting at 2 months of age. Blood pressure, urinary NO metabolites (NO(x)), and total renal NO synthase activity were monitored, and the tissue abundance of nitrotyrosine (NT), which is the stable "footprint" of NO oxidation by ROS, was determined. The HFS diet group exhibited a gradual rise in arterial blood pressure and were hypertensive by 18 months. This trend was accompanied by a marked accumulation of NT in all tested tissues, an initial rise and a subsequent fall in NO synthase activity, and a fall in urinary NO(x) excretion. The HFS diet-fed animals had a blunted blood pressure response to the NO synthase inhibitor N:(omega)-nitro-L-arginine methyl ester (L-NAME) compared with the LFCC diet group, which showed a marked hypertensive response to L-NAME. L-NAME-induced HTN was reversible with L-arginine in the LFCC diet group; however, HTN was not corrected by L-arginine supplementation in the HFS diet group. These findings point to enhanced ROS-mediated inactivation and sequestration of NO, which may contribute to the reduction of bioactive NO and HTN in the HFS diet-fed animals.

Topics: Animals; Arginine; Biomarkers; Blood Pressure; Body Weight; Dietary Carbohydrates; Dietary Fats; Enzyme Inhibitors; Female; Hypertension; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Oxidation-Reduction; Oxidative Stress; Rats; Rats, Inbred F344; Reactive Oxygen Species; Tyrosine

Our previous study demonstrated that the aortic inducible nitric oxide synthase (iNOS) expression and the plasma nitrite level in spontaneously hypertensive rats (SHR) were greater than that in age-matched Wistar-Kyoto rats (WKY). We subsequently hypothesized that the over-expression of iNOS might play an important role in the pathogenesis of hypertension in SHR. In the present study, pyrrolidinedithiocarbamate (PDTC, 10 mg kg(-1) day(-1), p.o., antioxidant and nuclear factor-kappa B inhibitor) and aminoguanidine (15 mg kg(-1) day(-1), p.o., selective inhibitor of iNOS) was used to treat SHR and WKY from age of 5 weeks through 16 weeks. We found that PDTC and aminoguanidine significantly suppressed the development of hypertension and improved the diminished vascular responses to acetylcholine in SHR but not in WKY. Likewise, the increase of iNOS expression, nitrotyrosine immunostaining, nitric oxide production and superoxide anion formation in adult SHR were also significantly suppressed by chronic treatment with PDTC and aminoguanidine. In conclusion, this study demonstrated that both PDTC and aminoguanidine significantly attenuated the development of hypertension in SHR. The results suggest that PDTC suppresses iNOS expression due to its anti-oxidant and/or nuclear factor-kappa B inhibitory properties. However, the effect of aminoguanidine was predominantly mediated by inhibition of iNOS activity, thereby reducing peroxynitrite formation. We propose that the development of a more specific and potent inhibitor of iNOS might be beneficial in preventing pathological conditions such as the essential hypertension.

Topics: Animals; Aorta; Blood Pressure; Disease Models, Animal; Enzyme Inhibitors; Guanidines; Hypertension; Immunoassay; Male; Nitrates; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Proline; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Superoxides; Thiocarbamates; Tyrosine; Vasodilation

The renin-angiotensin system is upregulated with diabetes, and this may contribute to the development of a dilated myopathy. Angiotensin II (Ang II) locally may lead to oxidative damage, activating cardiac cell death. Moreover, diabetes and hypertension could synergistically impair myocardial structure and function. Therefore, apoptosis and necrosis were measured in ventricular myocardial biopsies obtained from diabetic and diabetic-hypertensive patients. Accumulation of a marker of oxidative stress, nitrotyrosine, and Ang II labeling were evaluated quantitatively. The diabetic heart showed cardiac hypertrophy, cavitary dilation, and depressed ventricular performance. These alterations were more severe with diabetes and hypertension. Diabetes was characterized by an 85-fold, 61-fold, and 26-fold increase in apoptosis of myocytes, endothelial cells, and fibroblasts, respectively. Apoptosis in cardiac cells did not increase additionally with diabetes and hypertension. Diabetes increased necrosis by 4-fold in myocytes, 9-fold in endothelial cells, and 6-fold in fibroblasts. However, diabetes and hypertension increased necrosis by 7-fold in myocytes and 18-fold in endothelial cells. Similarly, Ang II labeling in myocytes and endothelial cells increased more with diabetes and hypertension than with diabetes alone. Nitrotyrosine localization in cardiac cells followed a comparable pattern. In spite of the difference in the number of nitrotyrosine-positive cells with diabetes and with diabetes and hypertension, apoptosis and necrosis of myocytes, endothelial cells, and fibroblasts were detected only in cells containing this modified amino acid. In conclusion, local increases in Ang II with diabetes and with diabetes and hypertension may enhance oxidative damage, activating cardiac cell apoptosis and necrosis.

Topics: Angiotensin II; Apoptosis; Cardiomegaly; Diabetes Mellitus, Type 2; Female; Heart Failure; Humans; Hypertension; Male; Middle Aged; Oxidative Stress; Reactive Oxygen Species; Renin-Angiotensin System; Tyrosine

Various proteins/enzymes obtained commercially were tested for the presence of endogenously nitrated tyrosine by Western blot analysis omitting reducing agent in the step of SDS-PAGE. Histones II-S and VIII-S, IgG, cAMP-dependent protein kinase (PKA), phosphorylase b, and phosphorylase kinase exhibited strong immunoreactive bands. Histone VI-S, glycogen synthase, lactate dehydrogenase, actin, thyroglobulin, and macroglobulin exhibited moderate immunoreactivity. Histone III-S, casein, acetyl cholinesterase, DNase I, and lipase had only traceable immunoreactivity. Whereas histone VII-S, pyruvate kinase, trypsin, pepsin, chymotrypsin, protease IV, and protease XIII, and glutathione S-transferase lacked immunoreactivity. A variation of immunoreactivity between hypertensive and normaltensive rat hearts was found in the histone-agarose fractions of crude extracts. Additionally, nitrotyrosine immunoreactivity was observed in non-mammalian organisms including Eschericia coli, Saccharomyces cerevisiae and Triticum vulgaris. Upon the treatment of 15 microM peroxynitrite (PN), strong oxidant derived from nitric oxide (NO), the apparent Km of PKA for cAMP increased from approximately 10(-8) to 10(-6) M. The results imply that the varied nitration of tyrosine residues in proteins/enzymes may occur as a post-translational modification in vivo, and such discriminative nitration may be vital in PN/NO-regulated signal transduction cascade.

Topics: Animals; Dogs; Hypertension; Immunohistochemistry; In Vitro Techniques; Male; Mice; Proteins; Rats; Rats, Inbred SHR; Tissue Distribution; Tyrosine