Nitric oxide function in atherosclerosis

Atherosclerosis is a chronic inflammatory process in the intima of conduit arteries, which disturbs the endothelium-dependent regulation of the vascular tone by the labile liposoluble radical nitric oxide (NO) formed by the constitutive endothelial nitric oxide synthase (eNOS). This defect predisposes to coronary vasospasm and cardiac ischaemia, with anginal pain as the typical clinical manifestation. It is now appreciated that endothelial dysfunction is an early event in atherogenesis and that it may also involve the microcirculation, in which atherosclerotic lesions do not develop. On the other hand, the inflammatory environment in atherosclerotic plaques may result in the expression of the inducible NO synthase (iNOS) isozyme. Whether the dysfunction in endothelial NO production is causal to, or the result of, atherosclerotic lesion formation is still highly debated. Most evidence supports the hypothesis that constitutive endothelial NO release protects against atherogenesis e.g. by preventing smooth muscle cell proliferation and leukocyte adhesion. Nitric oxide generated by the inducible isozyme may be beneficial by replacing the failing endothelial production but excessive release may damage the vascular wall cells, especially in combination with reactive oxygen intermediates.

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The Effect on Health of Some Cardiovascular Risk Factors

Revista de Chimie ◽

10.37358/rc.17.10.5863 ◽

2017 ◽

Vol 68 (10) ◽

pp. 2237-2242

Author(s):

Germaine Savoiu Balint ◽

Mihaiela Andoni ◽

Ramona Amina Popovici ◽

Laura Cristina Rusu ◽

Ioana Citu ◽

...

Keyword(s):

Nitric Oxide ◽

Vascular Reactivity ◽

Vascular Wall ◽

Dose Effect ◽

Organ Bath ◽

Before And After ◽

Specific Receptors ◽

Oxide Synthase ◽

Endothelial Nitric Oxide ◽

Relaxing Response

Arterial endothelium produces a large ramge of active factors which are indispensable for modulation of vasomotor tone and maintenance of vascular wall integrity. From these factors, nitric oxide (NO), wich is released by the endothelial cells as a response to acetylcholine or adenosine action on specific receptors, plays an important role.NO is the result of oxidation process of L-arginine into L-citrulline, under the action of endothelial nitric oxide synthase (NOSe), wich is activated by intracelluar Ca2+ - calmodulin complex . Our study, performed in isolated organ bath, analyzed vascular reactivity of 12 guinea pigs� thoracic aorta rings. After phenylephrine -PHE 10-5 mol/L precontraction, the dose-effect curves for acetylcoline � ACH, adenosine 5� phosphate - 5�ADP and sodium nitroprusside � SNP were determined, before and after incubation of preparation, for 1 hour, with 5% hydrosoluble cigarettes smoke extract (CSE). Statistic analysis, performed with the use of t pair test and ANOVA parametric test, showed that incubation of vascular preparation with 5% CSE has increased the contractile response to PHE 10-5 mol/L (p[0.05), has reduced the endothelium-dependent relaxing response to ATP 10-5 mol/L (p[0.001) and 5�ADP 10-5 molo/L (p[0.001), but has not significantly modified the endothelium-independent relaxing response to SNP 10-5 mol/L (p=0.05). As a conclusion, vascular rings incubation with 5% CSE induced a decrease of endothelium NO synthesis under the action of AXH and 5�ADP, but did not change the smooth muscle fiber respomse in the presence of NO released by SNP.

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Protein kinase Cδ regulates endothelial nitric oxide synthase expression via Akt activation and nitric oxide generation

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00353.2007 ◽

2008 ◽

Vol 294 (3) ◽

pp. L582-L591 ◽

Cited By ~ 9

Author(s):

Neetu Sud ◽

Stephen Wedgwood ◽

Stephen M. Black

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Endothelial Nitric Oxide Synthase ◽

Promoter Activity ◽

Dominant Negative ◽

No Production ◽

Enos Expression ◽

Akt Activation ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

In this study, we explore the roles of the delta isoform of PKC (PKCδ) in the regulation of endothelial nitric oxide synthase (eNOS) activity in pulmonary arterial endothelial cells isolated from fetal lambs (FPAECs). Pharmacological inhibition of PKCδ with either rottlerin or with the peptide, δV1-1, acutely attenuated NO production, and this was associated with a decrease in phosphorylation of eNOS at Ser1177 (S1177). The chronic effects of PKCδ inhibition using either rottlerin or the overexpression of a dominant negative PKCδ mutant included the downregulation of eNOS gene expression that was manifested by a decrease in both eNOS promoter activity and protein expression after 24 h of treatment. We also found that PKCδ inhibition blunted Akt activation as observed by a reduction in phosphorylated Akt at position Ser473. Thus, we conclude that PKCδ is actively involved in the activation of Akt. To determine the effect of Akt on eNOS signaling, we overexpressed a dominant negative mutant of Akt and determined its effect of NO generation, eNOS expression, and phosphorylation of eNOS at S1177. Our results demonstrated that Akt inhibition was associated with decreased NO production that correlated with reduced phosphorylation of eNOS at S1177, and decreased eNOS promoter activity. We next evaluated the effect of endogenously produced NO on eNOS expression by incubating FPAECs with the eNOS inhibitor 2-ethyl-2-thiopseudourea (ETU). ETU significantly inhibited NO production, eNOS promoter activity, and eNOS protein levels. Together, our data indicate involvement of PKCδ-mediated Akt activation and NO generation in maintaining eNOS expression.

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Effects of homocysteine on endothelial nitric oxide production

AJP Renal Physiology ◽

10.1152/ajprenal.2000.279.4.f671 ◽

2000 ◽

Vol 279 (4) ◽

pp. F671-F678 ◽

Cited By ~ 135

Author(s):

Xiaohui Zhang ◽

Hong Li ◽

Haoli Jin ◽

Zachary Ebin ◽

Sergey Brodsky ◽

...

Keyword(s):

Nitric Oxide ◽

Endothelial Cells ◽

Redox State ◽

Calcium Ionophore ◽

No Production ◽

Cellular Redox ◽

A Cell ◽

Oxide Synthase ◽

Endothelial Nitric Oxide ◽

Peroxynitrite Scavengers

Hyperhomocysteinemia (HHCy) is an independent and graded cardiovascular risk factor. HHCy is prevalent in patients with chronic renal failure, contributing to the increased mortality rate. Controversy exists as to the effects of HHCy on nitric oxide (NO) production: it has been shown that HHCy both increases and suppresses it. We addressed this problem by using amperometric electrochemical NO detection with a porphyrinic microelectrode to study responses of endothelial cells incubated with homocysteine (Hcy) to the stimulation with bradykinin, calcium ionophore, or l-arginine. Twenty-four-hour preincubation with Hcy (10, 20, and 50 μM) resulted in a gradual decline in responsiveness of endothelial cells to the above stimuli. Hcy did not affect the expression of endothelial nitric oxide synthase (eNOS), but it stimulated formation of superoxide anions, as judged by fluorescence of dichlorofluorescein, and peroxynitrite, as detected by using immunoprecipitation and immunoblotting of proteins modified by tyrosine nitration. Hcy did not directly affect the ability of recombinant eNOS to generate NO, but oxidation of sulfhydryl groups in eNOS reduced its NO-generating activity. Addition of 5-methyltetrahydrofolate restored NO responses to all agonists tested but affected neither the expression of the enzyme nor formation of nitrotyrosine-modified proteins. In addition, a scavenger of peroxynitrite or a cell-permeant superoxide dismutase mimetic reversed the Hcy-induced suppression of NO production by endothelial cells. In conclusion, electrochemical detection of NO release from cultured endothelial cells demonstrated that concentrations of Hcy >20 μM produce a significant indirect suppression of eNOS activity without any discernible effects on its expression. Folates, superoxide ions, and peroxynitrite scavengers restore the NO-generating activity to eNOS, collectively suggesting that cellular redox state plays an important role in HCy-suppressed NO-generating function of this enzyme.

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Endothelin stimulates endothelial nitric oxide synthase expression in the thick ascending limb

AJP Renal Physiology ◽

10.1152/ajprenal.00413.2003 ◽

2004 ◽

Vol 287 (2) ◽

pp. F231-F235 ◽

Cited By ~ 38

Author(s):

Marcela Herrera ◽

Jeffrey L. Garvin

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Receptor Antagonist ◽

Endothelial Nitric Oxide Synthase ◽

No Production ◽

Thick Ascending Limb ◽

Enos Expression ◽

No Release ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Endothelin-1 (ET-1) acutely inhibits NaCl reabsorption by the thick ascending limb (THAL) by activating the ETB receptor, stimulating endothelial nitric oxide synthase (eNOS), and releasing nitric oxide (NO). In nonrenal tissue, chronic exposure to ET-1 stimulates eNOS expression via the ETB receptor and activation of phosphatidylinositol 3-kinase (PI3K). We hypothesized that ET-1 increases eNOS expression in the THAL by binding to ETB receptors and stimulating PI3K. In primary cultures of medullary THALs treated for 24 h, eNOS expression increased by 36 ± 18% with 0.01 nM ET-1, 123 ± 30% with 0.1 nM ( P < 0.05; n = 5), and 71 ± 30% with 1 nM, whereas 10 nM had no effect. BQ-788, a selective ETB receptor antagonist, completely blocked stimulation of eNOS expression caused by 0.1 nM ET-1 (12 ± 25 vs. 120 ± 40% for ET-1 alone; P < 0.05; n = 5). BQ-123, a selective ETA receptor antagonist, did not affect the increase in eNOS caused by 0.1 nM ET-1. Sarafotoxin c (S6c; 0.1 μM), a selective ETB receptor agonist, increased eNOS expression by 77 ± 30% ( P < 0.05; n = 6). Wortmannin (0.01 μM), a PI3K inhibitor, completely blocked the stimulatory effect of 0.1 μM S6c (77 ± 30 vs. −28 ± 9%; P < 0.05; n = 6). To test whether the increase in eNOS expression heightens activity, we measured NO release in response to simultaneous treatment with l-arginine, ionomycin, and clonidine using a NO-sensitive electrode. NO release by control cells was 337 ± 61 and 690 ± 126 pA in ET-1-treated cells ( P < 0.05; n = 5). Taken together, these data suggest that ET-1 stimulates THAL eNOS, activating ETB receptors and PI3K and thereby increasing NO production.

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Cilostazol Induces eNOS and TM Expression via Activation with Sirtuin 1/Krüppel-like Factor 2 Pathway in Endothelial Cells

International Journal of Molecular Sciences ◽

10.3390/ijms221910287 ◽

2021 ◽

Vol 22 (19) ◽

pp. 10287

Author(s):

Chih-Hsien Wu ◽

Yi-Lin Chiu ◽

Chung-Yueh Hsieh ◽

Guo-Shiang Tsung ◽

Lian-Shan Wu ◽

...

Keyword(s):

Nitric Oxide ◽

Endothelial Cells ◽

Endothelial Nitric Oxide Synthase ◽

Umbilical Vein ◽

Sirtuin 1 ◽

No Production ◽

Beneficial Effects ◽

Umbilical Vein Endothelial Cells ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Cilostazol was suggested to be beneficial to retard in-stent atherosclerosis and prevent stent thrombosis. However, the mechanisms responsible for the beneficial effects of cilostazol are not fully understood. In this study, we attempted to verify the mechanism of the antithrombotic effect of cilostazol. Human umbilical vein endothelial cells (HUVECs) were cultured with various concentrations of cilostazol to verify its impact on endothelial cells. KLF2, silent information regulator transcript-1 (SIRT1), endothelial nitric oxide synthase (eNOS), and endothelial thrombomodulin (TM) expression levels were examined. We found cilostazol significantly activated KLF2 expression and KLF2-related endothelial function, including eNOS activation, Nitric oxide (NO) production, and TM secretion. The activation was regulated by SIRT1, which was also stimulated by cilostazol. These findings suggest that cilostazol may be capable of an antithrombotic and vasculoprotective effect in endothelial cells.

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Dysregulation of l-arginine metabolism and bioavailability associated to free plasma heme

AJP Cell Physiology ◽

10.1152/ajpcell.00405.2009 ◽

2010 ◽

Vol 299 (1) ◽

pp. C148-C154 ◽

Cited By ~ 38

Author(s):

F. Omodeo-Salè ◽

L. Cortelezzi ◽

Z. Vommaro ◽

D. Scaccabarozzi ◽

A. M. Dondorp

Keyword(s):

Nitric Oxide ◽

Severe Malaria ◽

Protoporphyrin Ix ◽

Plasmodium Falciparum Malaria ◽

No Production ◽

Cationic Amino Acid ◽

Rbc Membrane ◽

Free Heme ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Severe Plasmodium falciparum malaria is associated with hypoargininemia, which contributes to impaired systemic and pulmonary nitric oxide (NO) production and endothelial dysfunction. Since intravascular hemolysis is an intrinsic feature of severe malaria, we investigated whether and by which mechanisms free heme [Fe(III)-protoporphyrin IX (FP)] might contribute to the dysregulation of l-arginine (l-Arg) metabolism and bioavailability. Carrier systems “y+” [or cationic amino acid transporter (CAT)] and “y+L” transport l-Arg into red blood cells (RBC), where it is hydrolyzed to ornithine and urea by arginase (isoform I) or converted to NO· and citrulline by endothelial nitric oxide synthase (eNOS). Our results show a significant and dose-dependent impairment of l-Arg transport into RBC pretreated with FP, with a strong inhibition of the system carrier y+L. Despite the impaired l-Arg influx, higher amounts of l-Arg-derived urea are produced by RBC preexposed to FP caused by activation of RBC arginase I. This activation appeared not to be mediated by oxidative modifications of the enzyme. We conclude that l-Arg transport across RBC membrane is impaired and arginase-mediated l-Arg consumption enhanced by free heme. This could contribute to reduced NO production in severe malaria.

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Recombinant Gene Transfer of Endothelial Nitric Oxide Synthase Augments Coronary Artery Relaxations During Hypoxia

Circulation ◽

10.1161/circ.100.suppl_2.ii-335 ◽

1999 ◽

Vol 100 (suppl_2) ◽

Author(s):

David G. Cable ◽

Vincent J. Pompili ◽

Timothy O’Brien ◽

Hartzell V. Schaff

Keyword(s):

Nitric Oxide ◽

Coronary Artery ◽

Nitric Oxide Synthase ◽

Gene Transfer ◽

Coronary Arteries ◽

Endothelial Nitric Oxide Synthase ◽

No Production ◽

Viral Control ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Background —Coronary arteries respond to hypoxia with transient relaxations, which increases coronary blood flow, in part, by release of nitric oxide. We hypothesized that increased expression of nitric oxide synthase might further augment blood vessel relaxation during hypoxia. The present study examined the effect of adenovirus-mediated transfer of bovine endothelial nitric oxide synthase (eNOS) on hypoxia-induced transient relaxations in canine coronary arteries. Methods and Results —Paired segments of coronary arteries were exposed to vehicle (phosphate-buffered saline with albumin) or an adenovirus encoding either E coli β-galactosidase (Ad.CMVLacZ, viral control; 10 10 pfu/mL) or eNOS (Ad.CMVeNOS; 10 10 pfu/mL) for 2 hours at 37°C. Immunohistochemistry with a monoclonal antibody specific for eNOS documented both endothelial and adventitial expression in Ad.CMVeNOS arteries, whereas vehicle and viral controls demonstrated only constitutive expression. Levels of cGMP were increased 5-fold in Ad.CMVeNOS arteries compared with controls. In arteries exposed to Ad.CMVeNOS, maximum contraction to prostaglandin F 2α was reduced compared with viral controls, and this effect was eliminated by pretreatment with a competitive inhibitor of eNOS ( N G -monomethyl- l -arginine, 10 −3 mol/L). Hypoxia-induced transient relaxation (95% N 2 -5% CO 2 ) in Ad.CMVeNOS arteries (45.2±8.8%, n=6) was augmented compared with vehicle (26.3±6.0%) or viral (27.2±7.1%) controls. Conclusions —Adenovirus-mediated gene transfer of nitric oxide synthase reduces receptor-dependent contractions and augments hypoxia-induced relaxations in canine coronary arteries; this method of augmentation of NO production might be advantageous for reduction of coronary artery vasospasm.

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Abstract 111: Xanthine Oxidoreductase Plays a Key Role in Nitrate, Nitrite and Nitric Oxide Homeostasis When the Endothelial Nitric Oxide Synthase is Compromised

Hypertension ◽

10.1161/hyp.68.suppl_1.111 ◽

2016 ◽

Vol 68 (suppl_1) ◽

Author(s):

Maria Peleli ◽

Christa Zollbrecht ◽

Marcelo Montenegro ◽

Michael Hezel ◽

Eddie Weitzberg ◽

...

Keyword(s):

Nitric Oxide ◽

Blood Pressure ◽

Primary Source ◽

No Production ◽

Xanthine Oxidoreductase ◽

Physiological Conditions ◽

Inorganic Nitrate ◽

Nos Inhibitor ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Xanthine oxidoreductase (XOR) is generally known as a source of superoxide production, but this enzyme has also been suggested to mediate NO production via reduction of inorganic nitrate (NO 3 - ) and nitrite(NO 2 - ). This pathway for NO generation is of particular importance during certain pathologies, whereas endothelial NO synthase (eNOS) is the primary source of vascular NO generation under normal physiological conditions. The exact interplay between the NOS and XOR-derived NO is not yet fully elucidated. The aim of the present study was to investigate if eNOS deficiency is partly compensated by XOR upregulation and sensitization of the NO 3 - - NO 2 - - NO pathway. NO 3 - and NO 2 - were similar between naïve eNOS KO and wildtype (wt) mice, but reduced upon chronic treatment with the non-selective NOS inhibitor L-NAME (wt: 25.0±5.2, eNOS KO: 39.2±6.4, L-NAME: 8.2±1.6 μ NO 3 - -, wt: 0.38±0.07, eNOS KO: 0.42±0.04, L-NAME: 0.12±0.02 μ NO 2 - ). XOR function was upregulated in eNOS KO compared with wt mice [(mRNA: wt 1±0.07, eNOS KO 1.38±0.17), (activity: wt 825±54, eNOS KO 1327±280 CLU/mg/min), (uric acid: wt 32.87±1.53, eNOS KO 43.23±3.54 μ)]. None of these markers of XOR activity was increased in nNOS KO and iNOS KO mice. Following acute dose of NO 3 - (10 mg/kg bw, i.p.), the increase of plasma NO 2 - was more pronounced in eNOS KO (+0.51±0.13 μ) compared with wt (+0.22±0.09 μ), and this augmented response in the eNOS KO was abolished by treatment with the highly selective XOR inhibitor febuxostat (FEB). Liver from eNOS KO had higher reducing capacity of NO 2 - to NO compared with wt, and this effect was attenuated by FEB (Δppb of NO: wt +8.7±4.2, eNOS KO +44.2±15.0, wt+FEB +22.2±9.6, eNOS KO+FEB +26.8±10.2). Treatment with FEB increased blood pressure in eNOS KO (ΔMAP:+10.2±5.6 mmHg), but had no effect in wt (ΔMAP:-0.6±3.3 mmHg). Supplementation with NO 3 - (10 mM, drinking water) reduced blood pressure in eNOS KO (ΔMAP: -6.3±2.2 mmHg), and this effect was abolished by FEB (ΔMAP: +1.1±1.9 mmHg). In conclusion, upregulated and altered XOR function in conditions with eNOS deficiency can facilitate the NO 3 - - NO 2 - - NO pathway and hence play a significant role in vascular NO homeostasis.

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Early Alterations of Endothelial Nitric Oxide Synthase Expression Patterns in the Guinea Pig Cochlea After Noise Exposure

Journal of Histochemistry & Cytochemistry ◽

10.1369/0022155419876644 ◽

2019 ◽

Vol 67 (11) ◽

pp. 845-855

Author(s):

Ulf R. Heinrich ◽

Irene Schmidtmann ◽

Regina Meuser ◽

Benjamin P. Ernst ◽

Desiree Wünsch ◽

...

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Endothelial Nitric Oxide Synthase ◽

Noise Exposure ◽

Expression Patterns ◽

Microscopic Analysis ◽

No Production ◽

Apical Side ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Constitutively expressed endothelial nitric oxide synthase (eNOS) is supposed to play a role in noise-induced nitric oxide (NO)-production. It is commonly known that intense noise exposure results in inducible NOS (iNOS) expression and increased NO-production, but knowledge about a contribution of the eNOS isoform is still lacking. Effects of noise exposure on eNOS immunolabeling were determined in male guinea pigs ( n=24). For light microscopic analysis, 11 animals were exposed to 90 dB for 1 hr and 6 animals were used as controls. After exposure, eNOS immunostaining was performed on paraffin sections, and the staining intensities were quantified for 4 cochlear regions. For electron microscopic analysis, 2 animals were exposed for 2 hr to 90 dB and 5 animals were used as controls. The intensity of eNOS immunolabeling was found to be already comprehensively increased 1 hr after noise exposure to 90 dB. At the ultrastructural level, a clear increase in eNOS immunolabeling was found in microtubules-rich areas of cochlear cuticular structures. Hence, our findings indicate that the reticular lamina forming the endolymph–perilymph barrier at the apical side of the organ of Corti is involved in a fast intrinsic otoprotective mechanism of the cochlea.

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The Effects of Oral l-Arginine and l-Citrulline Supplementation on Blood Pressure

Nutrients ◽

10.3390/nu11071679 ◽

2019 ◽

Vol 11 (7) ◽

pp. 1679 ◽

Cited By ~ 8

Author(s):

David Khalaf ◽

Marcus Krüger ◽

Markus Wehland ◽

Manfred Infanger ◽

Daniela Grimm

Keyword(s):

Nitric Oxide ◽

Blood Pressure ◽

Animal Studies ◽

Current Data ◽

No Production ◽

First Pass Metabolism ◽

Oxide Synthase ◽

Endothelial Nitric Oxide ◽

Antihypertensive Properties ◽

Pass Metabolism

Nitric oxide (NO) is a well-known vasodilator produced by the vascular endothelium via the enzyme endothelial nitric oxide synthase (eNOS). The inadequate production of NO has been linked to elevated blood pressure (BP) in both human and animal studies, and might be due to substrate inaccessibility. This review aimed to investigate whether oral administration of the amino acids l-arginine (Arg) and l-citrulline (Cit), which are potential substrates for eNOS, could effectively reduce BP by increasing NO production. Both Arg and Cit are effective at increasing plasma Arg. Cit is approximately twice as potent, which is most likely due to a lower first-pass metabolism. The current data suggest that oral Arg supplementation can lower BP by 5.39/2.66 mmHg, which is an effect that is comparable with diet changes and exercise implementation. The antihypertensive properties of Cit are more questionable, but are likely in the range of 4.1/2.08 to 7.54/3.77 mmHg. The exact mechanism by which Cit and Arg exert their effect is not fully understood, as normal plasma Arg concentration greatly exceeds the Michaelis constant (Km) of eNOS. Thus, elevated plasma Arg concentrations would not be expected to increase endogenous NO production significantly, but have nonetheless been observed in other studies. This phenomenon is known as the “l-arginine paradox”.

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