title: Peroxynitrite disrupts endothelial caveolae leading to eNOS uncoupling and diminished flow-mediated dilation in coronary arterioles of diabetic patients.
abstract: Peroxynitrite (ONOO(-)) contributes to coronary microvascular dysfunction in diabetes mellitus (DM). We hypothesized that in DM, ONOO(-) interferes with the function of coronary endothelial caveolae, which plays an important role in nitric oxide (NO)-dependent vasomotor regulation. Flow-mediated dilation (FMD) of coronary arterioles was investigated in DM (n = 41) and non-DM (n = 37) patients undergoing heart surgery. NO-mediated coronary FMD was significantly reduced in DM patients, which was restored by ONOO(-) scavenger, iron-(III)-tetrakis(N-methyl-4'pyridyl)porphyrin-pentachloride, or uric acid, whereas exogenous ONOO(-) reduced FMD in non-DM subjects. Immunoelectron microscopy demonstrated an increased 3-nitrotyrosine formation (ONOO(-)-specific protein nitration) in endothelial plasma membrane in DM, which colocalized with caveolin-1 (Cav-1), the key structural protein of caveolae. The membrane-localized Cav-1 was significantly reduced in DM and also in high glucose-exposed coronary endothelial cells. We also found that DM patients exhibited a decreased number of endothelial caveolae, whereas exogenous ONOO(-) reduced caveolae number. Correspondingly, pharmacological (methyl-β-cyclodextrin) or genetic disruption of caveolae (Cav-1 knockout mice) abolished coronary FMD, which was rescued by sepiapterin, the stable precursor of NO synthase (NOS) cofactor, tetrahydrobiopterin. Sepiapterin also restored coronary FMD in DM patients. Thus, we propose that ONOO(-) selectively targets and disrupts endothelial caveolae, which contributes to NOS uncoupling, and, hence, reduced NO-mediated coronary vasodilation in DM patients.
authors.affiliation: Vascular Biology Center, Medical College of Georgia, Georgia Regents University, Augusta, GA.
authors.forename: James
authors.initials: J
authors.lastname: Cassuto
authors.forename: Huijuan
authors.initials: H
authors.lastname: Dou
authors.forename: Istvan
authors.initials: I
authors.lastname: Czikora
authors.forename: Andras
authors.initials: A
authors.lastname: Szabo
authors.forename: Vijay S
authors.initials: VS
authors.lastname: Patel
authors.forename: Vinayak
authors.initials: V
authors.lastname: Kamath
authors.forename: Eric
authors.initials: E
authors.lastname: Belin de Chantemele
authors.forename: Attila
authors.initials: A
authors.lastname: Feher
authors.forename: Maritza J
authors.initials: MJ
authors.lastname: Romero
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Bagi
mesh_terms: D000368:Aged; D000818:Animals; D001160:Arterioles / Q000503:physiopathology; D021941:Caveolae / Q000187:drug effects*; D051242:Caveolin 1 / Q000378:metabolism; D002478:Cells, Cultured; D003920:Diabetes Mellitus / Q000503:physiopathology*; D042783:Endothelial Cells / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000494:pharmacology*; D011622:Pterins / Q000494:pharmacology; D012039:Regional Blood Flow; D014443:Tyrosine / Q000031:analogs & derivatives; D014664:Vasodilation / Q000187:drug effects*; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D051242:Caveolin 1; D011622:Pterins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; C016727:sepiapterin; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III