title: Mechanisms of H2O2-induced oxidative stress in endothelial cells.
abstract: Hydrogen peroxide, produced by inflammatory and vascular cells, induces oxidative stress that may contribute to endothelial dysfunction. In smooth muscle cells, H(2)O(2) induces production of O(2)*(-) by activating NADPH oxidase. However, the mechanisms whereby H(2)O(2) induces oxidative stress in endothelial cells are poorly understood. We examined the effects of H(2)O(2) on O(2)*(-) levels on porcine aortic endothelial cells (PAEC). Treatment with 60 micromol/L H(2)O(2) markedly increased intracellular O(2)*(-) levels (determined by conversion of dihydroethidium to hydroxyethidium) and produced cytotoxicity (determined by propidium iodide staining) in PAEC. Overexpression of human manganese superoxide dismutase in PAEC reduced O(2)*(-) levels and attenuated cytotoxicity resulting from treatment with H(2)O(2). L-NAME, an inhibitor of nitric oxide synthase (NOS), and apocynin, an inhibitor of NADPH oxidase, reduced O(2)*(-) levels in PAEC treated with H(2)O(2), suggesting that both NOS and NADPH oxidase contribute to H(2)O(2)-induced O(2)*(-) in PAEC. Inhibition of NADPH oxidase using apocynin and NOS rescue with L-sepiapterin together reduced O(2)*(-) levels in PAEC treated with H(2)O(2) to control levels. This suggests interaction-distinct NOS and NADPH oxidase pathways to superoxide. We conclude that H(2)O(2) produces oxidative stress in endothelial cells by increasing intracellular O(2)*(-) levels through NOS and NADPH oxidase. These findings suggest a complex interaction between H(2)O(2) and oxidant-generating enzymes that may contribute to endothelial dysfunction.
authors.affiliation: Cell and Synthetic Interface Engineering Laboratory, Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Christian H
authors.initials: CH
authors.lastname: Coyle
authors.forename: Luis J
authors.initials: LJ
authors.lastname: Martinez
authors.forename: Mitchell C
authors.initials: MC
authors.lastname: Coleman
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Spitz
authors.forename: Neal L
authors.initials: NL
authors.lastname: Weintraub
authors.forename: Khalid N
authors.initials: KN
authors.lastname: Kader
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001011:Aorta / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018384:Oxidative Stress; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000032:analysis / Q000378:metabolism; D013552:Swine
chemical_list: D000098:Acetophenones; D000975:Antioxidants; D004791:Enzyme Inhibitors; D013481:Superoxides; C056165:acetovanillone; D006861:Hydrogen Peroxide; D019001:Nitric Oxide Synthase; D013482:Superoxide Dismutase; D019255:NADPH Oxidases; D019331:NG-Nitroarginine Methyl Ester