title: L-arginine enhances nitrative stress and exacerbates tumor necrosis factor-alpha toxicity to human endothelial cells in culture: prevention by propofol.
abstract: Supplementation of L-arginine, a nitric oxide precursor, during the late phase of myocardial ischemia/reperfusion increases myocyte apoptosis and exacerbates myocardial injury, but the underlying mechanism is unclear. During myocardial ischemia/reperfusion, apoptosis of endothelial cells precedes that of cardiomyocyte. Tumor necrosis factor-alpha (TNF) production is increased during myocardial ischemia/reperfusion, which may exacerbate myocardial injury by inducing endothelial cell apoptosis. We postulated that L-arginine may exacerbate TNF-induced endothelial cell apoptosis by enhancing peroxynitrite-mediated nitrative stress. Cultured human umbilical vein endothelial cells were either not treated (control) or treated with TNF alone or with TNF in the presence of L-arginine, the nonselective nitric oxide synthase inhibitor N (omega)-nitro-L-arginine (L-NNA), propofol (an anesthetic that scavenges peroxynitrite), or L-arginine plus propofol, respectively, for 24 hours. TNF increased intracellular superoxide and hydrogen peroxide production accompanied by increases of inducible nitric oxide synthase (iNOS) protein expression and nitric oxide production. This was accompanied by increased protein expression of nitrotyrosine, a fingerprint of peroxynitrite and an index of nitrative stress, and increased endothelial cell apoptosis. L-arginine did not enhance TNF-induced increases of superoxide and peroxynitrite production but further increased TNF-induced increase of nitrotyrosine production and exacerbated TNF-mediated cell apoptosis. L-NNA and propofol, respectively, reduced TNF-induced nitrative stress and attenuated TNF cellular toxicity. The L-arginine-mediated enhancement of nitrative stress and TNF toxicity was attenuated by propofol. Thus, under pathological conditions associated with increased TNF production, L-arginine supplementation may further exacerbate TNF cellular toxicity by enhancing nitrative stress.
authors.affiliation: Department of Anesthesiology and Research Centre of Heart, Brain, Hormone and Healthy Aging, University of Hong Kong, Hong Kong, China. zyxia@hku.hk
authors.forename: Zhengyuan
authors.initials: Z
authors.lastname: Xia
authors.forename: Tao
authors.initials: T
authors.lastname: Luo
authors.forename: Hui-min
authors.initials: HM
authors.lastname: Liu
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Zhong-yuan
authors.initials: ZY
authors.lastname: Xia
authors.forename: Michael G
authors.initials: MG
authors.lastname: Irwin
authors.forename: Paul M
authors.initials: PM
authors.lastname: Vanhoutte
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001120:Arginine / Q000494:pharmacology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005979:Glutathione Peroxidase / Q000378:metabolism; D006146:Guanidines / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D019335:Nitroarginine / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D015742:Propofol / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D006146:Guanidines; D009566:Nitrates; D009573:Nitrites; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D019335:Nitroarginine; C002744:3-nitrotyrosine; D014443:Tyrosine; D008315:Malondialdehyde; D001120:Arginine; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D005979:Glutathione Peroxidase; C496319:NOS2 protein, human; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D013482:Superoxide Dismutase; C004479:pimagedine; D015742:Propofol