Endothelial dysfunction and the expression of endothelial nitric oxide synthetase in diabetic neuropathy, vascular disease, and foot ulceration

Loss of peroxisome proliferator-activated receptor (PPAR)-γ function in the vascular endothelium enhances atherosclerosis and NF-κB target gene expression in high-fat diet-fed apolipoprotein E-deficient mice. The mechanisms by which endothelial PPAR-γ regulates inflammatory responses and protects against atherosclerosis remain unclear. To assess functional interactions between PPAR-γ and inflammation, we used a model of IL-1β-induced aortic dysfunction in transgenic mice with endothelium-specific overexpression of either wild-type (E-WT) or dominant negative PPAR-γ (E-V290M). IL-1β dose dependently decreased IκB-α, increased phospho-p65, and increased luciferase activity in the aorta of NF-κB-LUC transgenic mice. IL-1β also dose dependently reduced endothelial-dependent relaxation by ACh. The loss of ACh responsiveness was partially improved by pretreatment of the vessels with the PPAR-γ agonist rosiglitazone or in E-WT. Conversely, IL-1β-induced endothelial dysfunction was worsened in the aorta from E-V290M mice. Although IL-1β increased the expression of NF-κB target genes, NF-κB p65 inhibitor did not alleviate endothelial dysfunction induced by IL-1β. Tempol, a SOD mimetic, partially restored ACh responsiveness in the IL-1β-treated aorta. Notably, tempol only modestly improved protection in the E-WT aorta but had an increased protective effect in the E-V290M aorta compared with the aorta from nontransgenic mice, suggesting that PPAR-γ-mediated protection involves antioxidant effects. IL-1β increased ROS and decreased the phospho-endothelial nitric oxide synthase (Ser1177)-to-endothelial nitric oxide synthase ratio in the nontransgenic aorta. These effects were completely abolished in the aorta with endothelial overexpression of WT PPAR-γ but were worsened in the aorta with E-V290M even in the absence of IL-1β. We conclude that PPAR-γ protects against IL-1β-mediated endothelial dysfunction through a reduction of oxidative stress responses but not by blunting IL-1β-mediated NF-κB activity.

Download Full-text

Renal endothelial dysfunction and impaired autoregulation after ischemia-reperfusion injury result from excess nitric oxide

AJP Renal Physiology ◽

10.1152/ajprenal.00302.2005 ◽

2006 ◽

Vol 291 (3) ◽

pp. F619-F628 ◽

Cited By ~ 32

Author(s):

Zhengrong Guan ◽

Glenda Gobé ◽

Desley Willgoss ◽

Zoltán H. Endre

Keyword(s):

Nitric Oxide ◽

Renal Failure ◽

Angiotensin Ii ◽

Endothelial Dysfunction ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Artery Occlusion ◽

Tubuloglomerular Feedback ◽

Sprague Dawley ◽

Endothelial Nitric Oxide

Endothelial dysfunction in ischemic acute renal failure (IARF) has been attributed to both direct endothelial injury and to altered endothelial nitric oxide synthase (eNOS) activity, with either maximal upregulation of eNOS or inhibition of eNOS by excess nitric oxide (NO) derived from iNOS. We investigated renal endothelial dysfunction in kidneys from Sprague-Dawley rats by assessing autoregulation and endothelium-dependent vasorelaxation 24 h after unilateral (U) or bilateral (B) renal artery occlusion for 30 (U30, B30) or 60 min (U60, B60) and in sham-operated controls. Although renal failure was induced in all degrees of ischemia, neither endothelial dysfunction nor altered facilitation of autoregulation by 75 pM angiotensin II was detected in U30, U60, or B30 kidneys. Baseline and angiotensin II-facilitated autoregulation were impaired, methacholine EC50 was increased, and endothelium-derived hyperpolarizing factor (EDHF) activity was preserved in B60 kidneys. Increasing angiotensin II concentration restored autoregulation and increased renal vascular resistance (RVR) in B60 kidneys; this facilitated autoregulation, and the increase in RVR was abolished by 100 μM furosemide. Autoregulation was enhanced by Nω-nitro-l-arginine methyl ester. Peri-ischemic inhibition of inducible NOS ameliorated renal failure but did not prevent endothelial dysfunction or impaired autoregulation. There was no significant structural injury to the afferent arterioles with ischemia. These results suggest that tubuloglomerular feedback is preserved in IARF but that excess NO and probably EDHF produce endothelial dysfunction and antagonize autoregulation. The threshold for injury-producing, detectable endothelial dysfunction was higher than for the loss of glomerular filtration rate. Arteriolar endothelial dysfunction after prolonged IARF is predominantly functional rather than structural.

Download Full-text

Abstract MP56: Nitric Oxide-Therapy but Not Remote Ischemic Conditioning is Cerebroprotective in Stroke: A Study in Mouse Model of Endothelial Dysfunction and Hypertension

Stroke ◽

10.1161/str.52.suppl_1.mp56 ◽

2021 ◽

Vol 52 (Suppl_1) ◽

Author(s):

Syed M Zaidi ◽

Md Nasrul Hoda ◽

Farid Ahmed ◽

Heba Alkhatabi ◽

Muhammed H Al Qahtani

Keyword(s):

Nitric Oxide ◽

Endothelial Dysfunction ◽

Statistical Significance ◽

Intravenous Thrombolysis ◽

Once Daily ◽

Remote Ischemic Conditioning ◽

Ischemic Conditioning ◽

Stroke Models ◽

Endogenous Protection ◽

Endothelial Nitric Oxide

Background: Remote Ischemic Conditioning (RIC) was found effective in stroke models, likely via increased endothelial nitric oxide (NO); yet RIC failed to improve clinical outcomes ( NCT02342522 ; NCT02189928 ). We anticipated that comorbidities neutralize the benefits of RIC in stroke. Hypothesis: NO-therapy but not RIC is vasculoprotective in hypertensive stroke. Methods: Aged (18±1-mo old) S100A1-hets mutant (S100A +/- ) and wild-type (WT) mice were used. As needed, mice were treated with RIC, s-nitrosoglutathione (GSNO) reductase inhibitor (GRI; 5 mg/kg nebulized once daily for 2-wks), GSNO (100-ug/kg; nebulized once daily at 2h post-TES), and/or intravenous thrombolysis (IVT; 10mg/kg at 4h post-TES). Stroke and outcome measures were performed as mentioned below. Statistical significance was determined at P &lt 0.05. Results: S100A +/- compared to WT-type mice showed significantly higher mean arterial pressure (MAP) and lower plasma-NO, supporting a hypertensive phenotype with endothelial dysfunction in S100A +/- mice. In photothrombotic stroke (PTS), RIC significantly improved cerebral blood flow (CBF), behavior and reduced infarction in WT but not in S100A +/- mice at 48h. GRI in S100A +/- mice enhanced plasma NO, improved behavior and CBF, and reduced infarction significantly as compared to vehicle-treated S100A +/- at 48h post-PTS. RIC with GRI did not produce additive protection in S100A +/- mice at 48h post-PTS, demonstrating that the preservation of NO-pool with GRI protects against stroke, but RIC is not effective to enhance this endogenous protection in hypertensive mice. Moreover, GSNO nebulization but not RIC enhanced PbtO 2 , reduced BBB-leakage and brain hemoglobin (Hb)-content at 24h after thromboembolic stroke with and without IVT. Conclusions: NO-therapies but not RIC is effective in hypertensive stroke. RIC- and NO- therapies need further validation in comorbid stroke before embarking on the clinical trial.

Download Full-text

Potential pitfalls in analyzing structural uncoupling of eNOS: aging is not associated with increased enzyme monomerization

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00506.2018 ◽

2019 ◽

Vol 316 (1) ◽

pp. H80-H88 ◽

Cited By ~ 1

Author(s):

Fumin Chang ◽

Sheila Flavahan ◽

Nicholas A. Flavahan

Keyword(s):

Nitric Oxide ◽

Endothelial Dysfunction ◽

Nitric Oxide Synthase ◽

Endothelial Nitric Oxide Synthase ◽

Normal Activity ◽

Aortic Endothelial Cells ◽

Relative Expression ◽

Fischer 344 ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Homodimer formation is essential for the normal activity of endothelial nitric oxide synthase (eNOS). Structural uncoupling of eNOS, with generation of enzyme monomers, is thought to contribute to endothelial dysfunction in several vascular disorders, including aging. However, low-temperature SDS-PAGE of healthy arteries has revealed considerable variation between studies in the relative expression of eNOS dimers and monomers. While assessing structural uncoupling of eNOS in aging arteries, we identified methodological pitfalls that might contribute to such variation. Therefore, using human cultured aortic endothelial cells and aortas from young and aged Fischer-344 rats, we investigated optimal approaches for analyzing the expression of eNOS monomers and dimers. The results demonstrated that published differences in treatment of cell lysates can significantly impact the relative expression of several eNOS species, including denatured monomers, partially folded monomers, dimers, and higher-order oligomers. In aortas, experiments initially confirmed a large increase in eNOS monomers in aging arteries, consistent with structural uncoupling. However, these monomers were actually endogenous IgG, which, under these conditions, has mobility similar to eNOS monomers. Increased IgG levels in aged aortas likely reflect the aging-induced disruption of endothelial junctions and increased arterial penetration of IgG. After removal of the IgG signal, there were low levels of eNOS monomers in young arteries, which were not significantly different in aged arteries. Therefore, structural uncoupling of eNOS is not a prominent feature in young healthy arteries, and the process is not increased by aging. The study also identifies optimal approaches to analyze eNOS dimers and monomers. NEW & NOTEWORTHY Structural uncoupling of endothelial nitric oxide synthase (eNOS) is considered central to endothelial dysfunction. However, reported levels of eNOS dimers and monomers vary widely, even in healthy arteries. We demonstrate that sample processing can alter relative levels of eNOS species. Moreover, endothelial dysfunction in aging aortas results in IgG accumulation, which, because of similar mobility to eNOS monomers, could be misinterpreted as structural uncoupling. Indeed, enzyme monomerization is not prominent in young or aging arteries.

Download Full-text

Arginase Inhibition Restores Peroxynitrite-Induced Endothelial Dysfunction via L-Arginine-Dependent Endothelial Nitric Oxide Synthase Phosphorylation

Yonsei Medical Journal ◽

10.3349/ymj.2016.57.6.1329 ◽

2016 ◽

Vol 57 (6) ◽

pp. 1329 ◽

Cited By ~ 12

Author(s):

Minh Cong Nguyen ◽

Jong Taek Park ◽

Yeong Gwan Jeon ◽

Byeong Hwa Jeon ◽

Kwang Lae Hoe ◽

...

Keyword(s):

Nitric Oxide ◽

Endothelial Dysfunction ◽

Nitric Oxide Synthase ◽

Endothelial Nitric Oxide Synthase ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Download Full-text

Tackling endothelial dysfunction by modulating NOS uncoupling: new insights into its pathogenesis and therapeutic possibilities

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00540.2011 ◽

2012 ◽

Vol 302 (5) ◽

pp. E481-E495 ◽

Cited By ~ 125

Author(s):

Rinrada Kietadisorn ◽

Rio P. Juni ◽

An L. Moens

Keyword(s):

Nitric Oxide ◽

Endothelial Dysfunction ◽

Endothelial Function ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Therapeutic Interventions ◽

Enos Uncoupling ◽

Underlying Causes ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Endothelial nitric oxide synthase (eNOS) serves as a critical enzyme in maintaining vascular pressure by producing nitric oxide (NO); hence, it has a crucial role in the regulation of endothelial function. The bioavailability of eNOS-derived NO is crucial for this function and might be affected at multiple levels. Uncoupling of eNOS, with subsequently less NO and more superoxide generation, is one of the major underlying causes of endothelial dysfunction found in atherosclerosis, diabetes, hypertension, cigarette smoking, hyperhomocysteinemia, and ischemia/reperfusion injury. Therefore, modulating eNOS uncoupling by stabilizing eNOS activity, enhancing its substrate, cofactors, and transcription, and reversing uncoupled eNOS are attractive therapeutic approaches to improve endothelial function. This review provides an extensive overview of the important role of eNOS uncoupling in the pathogenesis of endothelial dysfunction and the potential therapeutic interventions to modulate eNOS for tackling endothelial dysfunction.

Download Full-text