scholarly journals Role of oxidative stress and AT1 receptors in cerebral vascular dysfunction with aging

2009 ◽  
Vol 296 (6) ◽  
pp. H1914-H1919 ◽  
Author(s):  
Mary L. Modrick ◽  
Sean P. Didion ◽  
Curt D. Sigmund ◽  
Frank M. Faraci

Vascular dysfunction occurs with aging. We hypothesized that oxidative stress and ANG II [acting via ANG II type 1 (AT1) receptors] promotes cerebral vascular dysfunction with aging. We studied young (5–6 mo), old (17–19 mo), and very old (23 ± 1 mo) mice. In basilar arteries in vitro, acetylcholine (an endothelium-dependent agonist) produced dilation in young wild-type mice that was reduced by ∼60 and 90% ( P < 0.05) in old and very old mice, respectively. Similar effects were seen using A23187, a second endothelium-dependent agonist. The vascular response to acetylcholine in very old mice was almost completely restored with tempol (a scavenger of superoxide) and partly restored by PJ34, an inhibitor of poly(ADP-ribose) polymerase (PARP). We used mice deficient in Mn-SOD (Mn-SOD+/−) to test whether this form of SOD protected during aging but found that age-induced endothelial dysfunction was not altered by Mn-SOD deficiency. Cerebral vascular responses were similar in young mice lacking AT1 receptors (AT1−/−) and wild-type mice. Vascular responses to acetylcholine and A23187 were reduced by ∼50% in old wild-type mice ( P < 0.05) but were normal in old AT1-deficient mice. Thus, aging produces marked endothelial dysfunction in the cerebral artery that is mediated by ROS, may involve the activation of PARP, but was not enhanced by Mn-SOD deficiency. Our findings suggest a novel and fundamental role for ANG II and AT1 receptors in age-induced vascular dysfunction.

2009 ◽  
Vol 296 (6) ◽  
pp. H1920-H1925 ◽  
Author(s):  
Donald D. Lund ◽  
Yi Chu ◽  
Jordan D. Miller ◽  
Donald D. Heistad

Endothelial vasomotor function decreases with increasing age. Extracellular superoxide dismutase (ecSOD) protects against vascular dysfunction in several disease states. The purpose of this study was to determine whether endogenous ecSOD protects against endothelial dysfunction in old mice. Vasomotor function of the aorta was studied ex vivo in wild-type (ecSOD+/+) and ecSOD-deficient (ecSOD−/−) mice at 11 (adult) and 29 (old) mo of age. Maximal relaxation to acetylcholine (10−4 M) was impaired in vessels from adult ecSOD−/− mice [75 ± 3% (mean ± SE)] compared with wild-type mice (89 ± 2%, P < 0.05). Maximal relaxation to acetylcholine (10−4 M) was profoundly impaired in aorta from old ecSOD−/− mice (45 ± 5%) compared with wild-type mice (75 ± 4%, P < 0.05). There was a significant correlation between expression of ecSOD and maximal relaxation to acetylcholine in adult and old mice. Tempol (1 mM), a scavenger of superoxide, improved relaxation in response to acetylcholine (63 ± 8%) in old ecSOD−/− mice ( P < 0.05), but not wild-type mice (75 ± 4%). Maximal relaxation to sodium nitroprusside was similar in aorta from adult and old wild-type and ecSOD−/− mice. Quantitative RT-PCR showed a decrease in mRNA levels of ecSOD and catalase in aorta of old mice and an increase in levels of TNFα and Nox-4 in aorta of old mice compared with adult mice. The findings support the hypothesis that impaired antioxidant mechanisms may contribute to cumulative increases in oxidative stress and impaired endothelial function in old mice. In conclusion, endogenous ecSOD plays an important role in protection against endothelial dysfunction during aging.


2000 ◽  
Vol 278 (4) ◽  
pp. H1311-H1319 ◽  
Author(s):  
Wilhelm Kossenjans ◽  
Annie Eis ◽  
Rashmi Sahay ◽  
Diane Brockman ◽  
Leslie Myatt

Oxidative stress may increase production of superoxide and nitric oxide, leading to formation of prooxidant peroxynitrite to cause vascular dysfunction. Having found nitrotyrosine residues, a marker of peroxynitrite action, in placental vessels of preeclamptic and diabetic pregnancies, we determined whether vasoreactivity is altered in these placentas and treatment with peroxynitrite produces vascular dysfunction. The responses of diabetic, preeclamptic, and normal placentas to increasing concentrations of the vasoconstrictors U-46619 (10− 9–10− 7M) and ANG II (10− 9–10− 7M) and the vasodilators glyceryl trinitrate (10− 9–10− 7M) and prostacyclin (PGI2; 10− 8–10− 6M) were compared as were responses to these agents in normal placentas before and after treatment with 3.16 × 10− 4 M peroxynitrite for 30 min. Responses to both vasoconstrictors and vasodilators were significantly attenuated in diabetic and preeclamptic placentas compared with controls. Similarly, responses to U-46619, nitroglycerin, and PGI2, but not ANG II, were significantly attenuated following peroxynitrite treatment. The presence of nitrotyrosine residues confirmed peroxynitrite interaction with placental vessels. Overall, our data suggest that peroxynitrite formation is capable of attenuating vascular responses in the human placenta.


Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Anna E Dikalova ◽  
Roman Uzhachenko ◽  
Hana A Itani ◽  
David G Harrison ◽  
Sergey Dikalov

Endothelial dysfunction is associated with aging, diabetes, hyperlipidemia, obesity and these risk factors affect the expression and activity of the mitochondrial deacetylase Sirt3. Sirt3 activates major antioxidant SOD2 by deacetylation of specific lysine residues and Sirt3 depletion increases oxidative stress. We hypothesized that loss of vascular Sirt3 increases endothelial dysfunction, promotes hypertension and end organ damage. The role of vascular Sirt3 was studied in wild-type C57Bl/6J mice and tamoxifen-inducible smooth muscle specific Sirt3 knockout mice (Smc Sirt3 KO ) using angiotensin II model of hypertension (Ang II, 0.7 mg/kg/day). Western blot showed 30% reduction of vascular Sirt3 and 2-fold increase in SOD2 acetylation in Ang II-infused WT mice. We have tested if ex vivo treatment of aorta with Sirt3 activator resveratrol improves endothelial function. Indeed, ex vivo incubation with resveratrol (10 μM) significantly reduced SOD2 acetylation, diminished mitochondrial O 2 and increased endothelial NO to normal level while Sirt3-inactive analog dihydroresveratrol had no effect. Specific role of vascular Sirt3 was studied in Smc Sirt3 KO mice by crossing floxed Sirt3 mice with mice carrying gene for inducible cre in the vascular smooth muscle. Sirt3 deletion exacerbates hypertension (165 mm Hg vs 155 mm Hg in wild-type) and significantly increases mortality in Ang II-infused Smc Sirt3 KO mice (60% vs 10% in wild-type) associated with severe edema and aortic aneurysm (100% vs 20% in wild-type). Decrease of NO is a hallmark of endothelial dysfunction in hypertension due to vascular oxidative stress. Indeed, Ang II infusion increased vascular O 2 by 2-fold and reduced endothelial NO by 2-fold. Interestingly, Ang II infusion in Smc Sirt3 KO mice caused severe vascular oxidative stress (3-fold increase in O 2 ) and exacerbated endothelial dysfunction (4-fold decrease in NO). These data indicate that reduced vascular Sirt3 activity occurs in hypertension and this promotes vascular oxidative stress, increases endothelial dysfunction, exacerbates hypertension, increases end-organ-damage and mortality. It is conceivable that Sirt3 agonists and SOD2 mimetics may have therapeutic potential in cardiovascular disease.


2012 ◽  
Vol 113 (2) ◽  
pp. 184-191 ◽  
Author(s):  
Sophocles Chrissobolis ◽  
Botond Banfi ◽  
Christopher G. Sobey ◽  
Frank M. Faraci

Angiotensin II (Ang II) promotes vascular disease through several mechanisms including by producing oxidative stress and endothelial dysfunction. Although multiple potential sources of reactive oxygen species exist, the relative importance of each is unclear, particularly in individual vascular beds. In these experiments, we examined the role of NADPH oxidase (Nox1 and Nox2) in Ang II-induced endothelial dysfunction in the cerebral circulation. Treatment with Ang II (1.4 mg·kg−1·day−1 for 7 days), but not vehicle, increased blood pressure in all groups. In wild-type (WT; C57Bl/6) mice, Ang II reduced dilation of the basilar artery to the endothelium-dependent agonist acetylcholine compared with vehicle but had no effect on responses in Nox2-deficient (Nox2−/y) mice. Ang II impaired responses to acetylcholine in Nox1 WT (Nox1+/y) and caused a small reduction in responses to acetylcholine in Nox1-deficient (Nox1−/y) mice. Ang II did not impair responses to the endothelium-independent agonists nitroprusside or papaverine in either group. In WT mice, Ang II increased basal and phorbol-dibutyrate-stimulated superoxide production in the cerebrovasculature, and these increases were abolished in Nox2−/y mice. Overall, these data suggest that Nox2 plays a relatively prominent role in mediating Ang II-induced oxidative stress and cerebral endothelial dysfunction, with a minor role for Nox1.


Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Arvind K Pandey ◽  
Hana A Itani ◽  
Liang Xiao ◽  
Annet Kirabo ◽  
Sergey Dikalov ◽  
...  

Oxidative stress is an important contributor to hypertension. Our group has shown that oxidative stress generates isolevuglandins (isoLG) that modify proteins and that these isoLG-modified proteins seem to act as neoantigens to promote hypertension. In addition to proteins, isoLG can also modify phosphatidylethanolamines (PEs). IsoLG-modified PE (IsoLG-PE) can in turn activate immune cells via reactions with toll-like receptors and downstream pathways including NFκB. The role of isoLG-PE in hypertension has not yet been defined. We have previously shown that the enzyme N-acyl-phosphatidylethanolamine-phospholipase D (NAPE-PLD) cleaves isoLG-PE, and mice lacking this enzyme have elevated cellular levels of isoLG-PE. To assess whether loss of NAPE-PLD and resulting increase in isoLG-PE contributes to hypertension, we infused wild type (WT) and NAPE-PLD -/- mice with low dose Ang II. We found baseline blood pressure was elevated in NAPE-PLD -/- mice compared to WT mice (128 ± 3 vs 111 ± 2 mmHg, p = 0.005) and that the increase in BP to low dose Ang II infusion (140 ng/kg/min) was augmented in NAPE-PLD -/- compared to WT mice (146 ± 9 vs 127 ± 4 mmHg, p=0.045). Endothelium-dependent vascular relaxation of the mesenteric arterioles to acetylcholine was impaired in NAPE-PLD -/- compared to WT mice (maximum relaxation of 43% ± 6% vs 53% ± 5%, p= 0.004), but endothelium-independent responses to sodium nitroprusside were similar in both groups (82% ± 2% in NAPE-PLD -/- mice vs 81% ± 4% in WT mice). Aortic adventitial collagen content by planimetry was likewise increased in NAPE-PLD -/- versus WT mice following low-dose Ang II. These studies in mice lacking NAPE-PLD suggest that in addition to exerting its effects via protein modification to form neo-antigens, the reaction of isoLG with PE and related phospholipids can augment hypertension, alter endothelium-dependent vasodilatation and promote vascular fibrosis.


2008 ◽  
Vol 294 (4) ◽  
pp. H1562-H1570 ◽  
Author(s):  
Hélène Bulckaen ◽  
Gaétan Prévost ◽  
Eric Boulanger ◽  
Géraldine Robitaille ◽  
Valérie Roquet ◽  
...  

The age-related impairment of endothelium-dependent vasodilatation contributes to increased cardiovascular risk in the elderly. For primary and secondary prevention, aspirin can reduce the incidence of cardiovascular events in this patient population. The present work evaluated the effect of low-dose aspirin on age-related endothelial dysfunction in C57B/J6 aging mice and investigated its protective antioxidative effect. Age-related endothelial dysfunction was assessed by the response to acetylcholine of phenylephrine-induced precontracted aortic segments isolated from 12-, 36-, 60-, and 84-wk-old mice. The effect of low-dose aspirin was examined in mice presenting a decrease in endothelial-dependent relaxation (EDR). The effects of age and aspirin treatment on structural changes were determined in mouse aortic sections. The effect of aspirin on the oxidative stress markers malondialdehyde and 8-hydroxy-2′-deoxyguanosine (8-OhdG) was also quantified. Compared with that of 12-wk-old mice, the EDR was significantly reduced in 60- and 84-wk-old mice ( P < 0.05); 68-wk-old mice treated with aspirin displayed a higher EDR compared with control mice of the same age (83.9 ± 4 vs. 66.3 ± 5%; P < 0.05). Aspirin treatment decreased 8-OHdG levels ( P < 0.05), but no significant effect on intima/media thickness ratio was observed. The protective effect of aspirin was not observed when treatment was initiated in older mice (96 wk of age). It was found that low-dose aspirin is able to prevent age-related endothelial dysfunction in aging mice. However, the absence of this effect in the older age groups demonstrates that treatment should be initiated early on. The underlying mechanism may involve the protective effect of aspirin against oxidative stress.


Hypertension ◽  
2021 ◽  
Vol 78 (Suppl_1) ◽  
Author(s):  
Dan Wang ◽  
Christopher S Wilcox

Introduction and hypothesis: Following bodily entry, the SARS-CoV-2 virus undergoes pulmonary replication with release of circulating viral spike protein 1 (SP1) into the bloodstream. Uptake of SP1 by endothelial cells might provoke vascular dysfunction and thrombosis. We hypothesized that spironolactone could prevent microvascular complications from circulating SP1 in COVID-19. Methods: male C57Bl/6 mice received spironolactone (100 mg · kg -1 · d -1 PO x 3d) or vehicle and intravenous injections of recombinant full-length human SP1 (10 μg per mouse) or vehicle. They were euthanized after 3 days. Mesenteric resistant arterioles (n=4 per group) were dissected and mounted on isometric myographs. Acetylcholine-induced EDRF responses and L-NAME-inhibitable NO generation (DAF-FM fluorescence) were studied in pre-constricted vessels and contraction to endothelin 1 (ET1) or thromboxane (U-46, 619) and ET1-induced ROS (PEG-SOD inhibitable ethidium: dihydroethidium fluorescence) were studied by fluorescence microscopy in other vessels. Results: SP1 reduced acetylcholine-induced EDRF (17 ± 3 vs 27 ± 5 % mean ± sem; P < 0.05) and NO generation (0.21 ± 0.03 vs 0.36 ± 0.04, F 1 /F 0 ; P < 0.05) while increasing contraction to ET1 (10 -7 mol·l -1 : 124 ± 13 vs 89 ± 4 %; P < 0.05) and U-46, 619 (10 -6 mol·l -1 :114± 5 vs 87± 6 %; P < 0.05) and ET1-induced ROS generation(0.30± 0.08 vs 0.09± 0.03; P < 0.05). Spironolactone did not modify any of these responses in vessels from normal mice but prevented all the effects of SP1. Conclusion: these preliminary studies provide a novel model to study COVID-19 vasculopathy. They indicate that spironolactone can provide protection from microvascular oxidative stress, endothelial dysfunction and enhanced contractility and might thereby moderate COVID-19 complications.


2017 ◽  
Vol 114 (2) ◽  
pp. 312-323 ◽  
Author(s):  
Sebastian Steven ◽  
Mobin Dib ◽  
Michael Hausding ◽  
Fatemeh Kashani ◽  
Matthias Oelze ◽  
...  

Abstract Aims CD40 ligand (CD40L) signaling controls vascular oxidative stress and related dysfunction in angiotensin-II-induced arterial hypertension by regulating vascular immune cell recruitment and platelet activation. Here we investigated the role of CD40L in experimental hyperlipidemia. Methods and results Male wild type and CD40L−/− mice (C57BL/6 background) were subjected to high fat diet for sixteen weeks. Weight, cholesterol, HDL, and LDL levels, endothelial function (isometric tension recording), oxidative stress (NADPH oxidase expression, dihydroethidium fluorescence) and inflammatory parameters (inducible nitric oxide synthase, interleukin-6 expression) were assessed. CD40L expression, weight, leptin and lipids were increased, and endothelial dysfunction, oxidative stress and inflammation were more pronounced in wild type mice on a high fat diet, all of which was almost normalized by CD40L deficiency. Similar results were obtained in diabetic db/db mice with CD40/TRAF6 inhibitor (6877002) therapy. In a small human study higher serum sCD40L levels and an inflammatory phenotype were detected in the blood and Aorta ascendens of obese patients (body mass index > 35) that underwent by-pass surgery. Conclusion CD40L controls obesity-associated vascular inflammation, oxidative stress and endothelial dysfunction in mice and potentially humans. Thus, CD40L represents a therapeutic target in lipid metabolic disorders which is a leading cause in cardiovascular disease.


2018 ◽  
Vol 315 (3) ◽  
pp. F583-F594 ◽  
Author(s):  
Wasan Abdulmahdi ◽  
May M. Rabadi ◽  
Edson Jules ◽  
Yara Marghani ◽  
Noor Marji ◽  
...  

Maternal undernutrition (MUN) during pregnancy leads to low-birth weight (LBW) neonates that have a reduced kidney nephron endowment and higher morbidity as adults. Using a severe combined caloric and protein-restricted mouse model of MUN to generate LBW mice, we examined the progression of renal insufficiency in LBW adults. Through 6 mo of age, LBW males experienced greater albuminuria (ELISA analysis), a more rapid onset of glomerular hypertrophy, and a worse survival rate than LBW females. In contrast, both sexes experienced a comparable progressive decline in renal vascular density (immunofluorescence analysis), renal blood flow (Laser-Doppler flowmetry analysis), glomerular filtration rate (FITC-sinistrin clearance analysis), and a progressive increase in systemic blood pressure (measured via tail-cuff method). Isolated aortas from both LBW sexes demonstrated reduced vasodilation in response to ACh, indicative of reduced nitric oxide bioavailability and endothelial dysfunction. ELISA and immunofluorescence analysis revealed a significant increase of circulating reactive oxygen species and NADPH oxidase type 4 (NOX4) expression in both LBW sexes, although these increases were more pronounced in males. Although more effective in males, chronic tempol treatment did improve all observed pathologies in both sexes of LBW mice. Chronic NOX4 inhibition with GKT137831 was more effective than tempol in preventing pathologies in LBW males. In conclusion, despite some minor differences, LBW female and male adults have a reduced nephron endowment comparable with progressive renal and vascular dysfunction, which is associated with increased oxidative stress and subsequent endothelial dysfunction. Tempol treatment and/or NOX4 inhibition attenuates renal and vascular dysfunction in LBW adults.


2019 ◽  
Vol 316 (3) ◽  
pp. H639-H646 ◽  
Author(s):  
Sergey Dikalov ◽  
Hana Itani ◽  
Bradley Richmond ◽  
Liaison Arslanbaeva ◽  
Aurelia Vergeade ◽  
...  

Tobacco smoking is a major risk factor for cardiovascular disease and hypertension. It is associated with the oxidative stress and induces metabolic reprogramming, altering mitochondrial function. We hypothesized that cigarette smoke induces cardiovascular mitochondrial oxidative stress, which contributes to endothelial dysfunction and hypertension. To test this hypothesis, we studied whether the scavenging of mitochondrial H2O2 in transgenic mice expressing mitochondria-targeted catalase (mCAT) attenuates the development of cigarette smoke/angiotensin II-induced mitochondrial oxidative stress and hypertension compared with wild-type mice. Two weeks of exposure of wild-type mice with cigarette smoke increased systolic blood pressure by 17 mmHg, which was similar to the effect of a subpresssor dose of angiotensin II (0.2 mg·kg−1·day−1), leading to a moderate increase to the prehypertensive level. Cigarette smoke exposure and a low dose of angiotensin II cooperatively induced severe hypertension in wild-type mice, but the scavenging of mitochondrial H2O2 in mCAT mice completely prevented the development of hypertension. Cigarette smoke and angiotensin II cooperatively induced oxidation of cardiolipin (a specific biomarker of mitochondrial oxidative stress) in wild-type mice, which was abolished in mCAT mice. Cigarette smoke and angiotensin II impaired endothelium-dependent relaxation and induced superoxide overproduction, which was diminished in mCAT mice. To mimic the tobacco smoke exposure, we used cigarette smoke condensate, which induced mitochondrial superoxide overproduction and reduced endothelial nitric oxide (a hallmark of endothelial dysfunction in hypertension). Western blot experiments indicated that tobacco smoke and angiotensin II reduce the mitochondrial deacetylase sirtuin-3 level and cause hyperacetylation of a key mitochondrial antioxidant, SOD2, which promotes mitochondrial oxidative stress. NEW & NOTEWORTHY This work demonstrates tobacco smoking-induced mitochondrial oxidative stress, which contributes to endothelial dysfunction and development of hypertension. We suggest that the targeting of mitochondrial oxidative stress can be beneficial for treatment of pathological conditions associated with tobacco smoking, such as endothelial dysfunction, hypertension, and cardiovascular diseases. Listen to this article’s corresponding podcast at https://ajpheart.podbean.com/e/mitochondrial-oxidative-stress-in-smoking-and-hypertension/ .


Sign in / Sign up

Export Citation Format

Share Document