title: Mechanism of nitric oxide production induced by H2O2 in cultured endothelial cells.
abstract: This study examined the mechanism of stimulation of nitric oxide (NO) synthesis induced by hydrogen peroxide (H2O2). To determine the role of Ca2+ on H2O2-induced NO synthesis in bovine aortic endothelial cells, the increases in intracellular Ca2+ and NO production induced by H2O2 were compared with the effects of the Ca2+ ionophore ionomycin in the same batches of endothelial cells. NO production was assessed by formation of [3H]citrulline from [3H]arginine, and changes in intracellular Ca2+ were measured using fluorescent indicator fluo-3 with a confocal laser scanning system. Both H2O2 (1-10 mM) and ionomycin (10(-7)-10(-5) M) increased intracellular Ca2+ and stimulated the synthesis of L-citrulline from L-arginine. Although H2O2 induced only a small increase in intracellular Ca2+, it markedly increased L-citrulline formation compared with ionomycin. Thus, stimulation of NO synthesis induced by H2O2 may involve the mechanisms other than the increases in intracellular Ca2+ in endothelial cells. In the particulate fraction from cultured endothelial cells, addition of exogenous H2O2 (1 mM) or catalase (100 U/ml) did not affect L-citrulline formation. However, co-administration of H2O2 and catalase stimulated L-citrulline formation. These findings suggested that not only the increases in intracellular Ca2+ but also the products by the reaction with H2O2 and catalase are likely to be involved in the stimulation of NO synthesis induced by H2O2.
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Shimizu
authors.forename: M
authors.initials: M
authors.lastname: Ishii
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Momose
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry; D000818:Animals; D001013:Aorta, Thoracic; D001120:Arginine / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002374:Catalase / Q000494:pharmacology; D002417:Cattle; D002458:Cell Fractionation; D002478:Cells, Cultured; D002956:Citrulline / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D005456:Fluorescent Dyes / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D007553:Isotope Labeling; D018613:Microscopy, Confocal; D009569:Nitric Oxide / Q000096:biosynthesis*; D016877:Oxidants / Q000494:pharmacology*; D014316:Tritium; D014966:Xanthenes / Q000737:chemistry
chemical_list: D000814:Aniline Compounds; D005456:Fluorescent Dyes; D007476:Ionophores; D016877:Oxidants; D014966:Xanthenes; D014316:Tritium; C059715:Fluo-3; D002956:Citrulline; D009569:Nitric Oxide; D015759:Ionomycin; D001120:Arginine; D006861:Hydrogen Peroxide; D002374:Catalase; D002118:Calcium