title: Antioxidants inhibit human endothelial cell functions through down-regulation of endothelial nitric oxide synthase activity.
abstract: We have recently shown that superoxide and hydrogen peroxide are putative inducers of angiogenesis in vivo, possibly through up regulation of inducible nitric oxide synthase (NOS) and increased production of endogenous nitric oxide (NO). The aim of the present work was to elucidate the implication of reactive oxygen species in endothelial cell functions, using cultures of human umbilical vein endothelial cells (HUVEC). Superoxide dismutase (SOD), tempol (membrane permeable SOD mimetic) and the NADPH oxidase inhibitors, 4-(2-aminoethyl)-benzenesulfonyl fluoride and apocynin, but not allopurinol, inhibited HUVEC proliferation and migration, as well as activity of endothelial NOS (eNOS). Catalase and the intracellular hydrogen peroxide scavenger sodium pyruvate decreased, while hydrogen peroxide increased HUVEC proliferation, migration and activity of eNOS. Dexamethasone induced the proliferation and migration of HUVEC and activated eNOS. Nomega-nitro-L-arginine methyl ester (L-NAME), but not Nomega-nitro-D-arginine methyl ester, decreased endothelial cell functions and reversed the effects of dexamethasone and hydrogen peroxide. N5-(1-iminoethyl)-L-ornithine dihydrochloride, but not the inducible NOS specific inhibitor N-[[3-(aminomethyl)phenyl]methyl]-ethanimidamide dihydrochloride also decreased endothelial cell functions, similarly to L-NAME. The guanylate cyclase inhibitor 1H-[1,2,4]Oxadiazole[4,3-a]quinoxalin-1-one inhibited HUVEC proliferation in a concentration-dependent manner and completely reversed hydrogen peroxide-induced proliferation, migration and cGMP accumulation. In conclusion, superoxide and hydrogen peroxide seem to play a significant role in promoting endothelial cell proliferation and migration, possibly through regulation of eNOS activity.
authors.affiliation: Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, GR 26504, Greece.
authors.forename: Christos
authors.initials: C
authors.lastname: Polytarchou
authors.forename: Evangelia
authors.initials: E
authors.lastname: Papadimitriou
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D002374:Catalase / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D003497:Cyclic N-Oxides / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000737:chemistry / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D010766:Phosphorylation / Q000187:drug effects; D011773:Pyruvates / Q000494:pharmacology; D013113:Spin Labels; D013237:Stereoisomerism; D013450:Sulfones / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000494:pharmacology
chemical_list: D000098:Acetophenones; D000975:Antioxidants; D003497:Cyclic N-Oxides; D004791:Enzyme Inhibitors; D011773:Pyruvates; D013113:Spin Labels; D013450:Sulfones; C002010:4-(2-aminoethyl)benzenesulfonylfluoride; D003907:Dexamethasone; C056165:acetovanillone; D006861:Hydrogen Peroxide; D002374:Catalase; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D013482:Superoxide Dismutase; D006152:Cyclic GMP; C001803:tempol; D019331:NG-Nitroarginine Methyl Ester