title: N-hydroxylamine is not an intermediate in the conversion of L-arginine to an activator of soluble guanylate cyclase in neuroblastoma N1E-115 cells.
abstract: This study evaluates the role of N-hydroxylamine (NH2OH) in activating soluble guanylate cyclase in the mouse neuroblastoma clone N1E-115. It has been proposed that NH2OH is a putative intermediate in the biochemical pathway for the generation of nitric oxide (NO)/endothelium-derived relaxing factor (EDRF) from L-arginine. NH2OH caused a time- and concentration-dependent increase in cyclic GMP formation in intact cells. This response was not dependent on Ca2+. In cytosol preparations the activation of guanylate cyclase by L-arginine was dose-dependent and required Ca2+ and NADPH. In contrast, NH2OH itself did not activate cytosolic guanylate cyclase but it inhibited the basal activity of this enzyme in a concentration-dependent manner. The formation of cyclic GMP in the cytosolic fractions in response to NH2OH required the addition of catalase and H2O2. On the other hand, catalase and/or H2O2 lead to a decrease in L-arginine-induced cyclic GMP formation. Furthermore, NH2OH inhibited L-arginine- and sodium nitroprusside-induced cyclic GMP formation in the cytosol. The inhibition of L-arginine-induced cyclic GMP formation in the cytosol by NH2OH was not reversed by the addition of superoxide dismutase. These data strongly suggest that NH2OH is not a putative intermediate in the metabolism of L-arginine to an activator of guanylate cyclase.
authors.affiliation: Department of Pharmacology and Toxicology, University of Maryland School of Pharmacy, Baltimore 21201.
authors.forename: S
authors.initials: S
authors.lastname: Pou
authors.forename: W S
authors.initials: WS
authors.lastname: Pou
authors.forename: G M
authors.initials: GM
authors.lastname: Rosen
authors.forename: E E
authors.initials: EE
authors.lastname: el-Fakahany
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D002460:Cell Line; D006152:Cyclic GMP / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D006162:Guanylate Cyclase / Q000378:metabolism*; D019811:Hydroxylamine; D006898:Hydroxylamines / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D009447:Neuroblastoma
chemical_list: D006898:Hydroxylamines; D019811:Hydroxylamine; D001120:Arginine; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D002118:Calcium