title: Analysis of agonist-evoked nitric oxide release from human endothelial cells: role of superoxide anion.
abstract: 1. Dichlorofluorescein oxidation and electrochemical monitoring of in situ nitric oxide (NO) release from cultured human endothelial cells reveals that agonists such as thrombin and histamine simultaneously stimulate transient superoxide production. 2. The duration of *NO release was increased only in the simultaneous presence of extracellular L-arginine and exogenous superoxide dismutase. In contrast, the inhibition of membrane reduced nicotinamide adenine dinucleotide (phosphate) oxidases, the major source of *O2- in endothelial cells, did not prolong *NO release, although extracellular L-arginine was also present. Comparison of these two experimental conditions suggested that H2O2 was involved in the extension of the *NO signal. 3. The present study demonstrates that, in the absence of external L-arginine, *O2- production does not constitute the major pathway controlling the duration of agonist-induced *NO signal. These results suggest that L-arginine and H2O2 act jointly to maintain nitric oxide synthase in an activated form.
authors.affiliation: Département de Pharmacologie, UMR 8604, Université René Descartes, Faculté de Médecine Necker, Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: David-Dufilho
authors.forename: A
authors.initials: A
authors.lastname: Brunet
authors.forename: C
authors.initials: C
authors.lastname: Privat
authors.forename: M A
authors.initials: MA
authors.lastname: Devynck
mesh_terms: D001120:Arginine / Q000494:pharmacology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005453:Fluorescence; D006632:Histamine / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D013481:Superoxides; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D006632:Histamine; D001120:Arginine; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D013917:Thrombin