title: Selective guanylyl cyclase inhibitor reverses nitric oxide-induced vasorelaxation.
abstract: Effects of a novel soluble guanylyl cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), were characterized on guanylyl cyclase activity in cytosolic fraction of COS-7 cells overexpressing the alpha 1 and beta 1 subunits of the rat soluble enzyme. ODQ was a noncompetitive inhibitor of soluble guanylyl cyclase with respect to Mn2+ or Mn(2+)-GTP and was a mixed competitive/noncompetitive inhibitor with respect to nitric oxide (NO) donation. ODQ (10 mumol/L) reduced deta nonoate-stimulated cGMP production in COS-7 cells overexpressing soluble guanylyl cyclase and in rat aortic vascular smooth muscle cells. ODQ did not inhibit particulate forms of the enzyme rat guanylyl cyclase-A, -B, or -C, did not block NO synthase, and did not auto-oxidize deta nonoate-donated NO in the presence of cells at physiological pH. Therefore, ODQ is a selective inhibitor of soluble guanylyl cyclase. Using ODQ in isolated aortic ring preparations, we tested the hypothesis that soluble guanylyl cyclase mediates vasorelaxant activity associated with NO. Phenylephrine (100 nmol/L)-precontracted, isolated rat aortas were relaxed in a concentration-dependent manner by deta nonoate (0.01 to 100 mumol/L) and nitroglycerin (0.01 to 300 mumol/L). ODQ (10 mumol/L) attenuated deta nonoate- and nitroglycerin-mediated relaxation of contracted aortas. ODQ had no effect on natriuretic peptide-, 8-bromo-cGMP-, isoproterenol-, or bimakalim-mediated aortic relaxation. These results support the hypothesis that soluble guanylyl cyclase mediates vasorelaxant activity associated with nitric oxide.
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee 53226-4801, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Olson
authors.forename: E T
authors.initials: ET
authors.lastname: Knych
authors.forename: T C
authors.initials: TC
authors.lastname: Herzig
authors.forename: J G
authors.initials: JG
authors.lastname: Drewett
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects; D019556:COS Cells / Q000378:metabolism; D006152:Cyclic GMP / Q000096:biosynthesis*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005996:Nitroglycerin / Q000494:pharmacology; D009603:Nitroso Compounds / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010656:Phenylephrine / Q000037:antagonists & inhibitors; D011810:Quinoxalines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019820:Xanthine; D014969:Xanthine Oxidase / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology
chemical_list: C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D009603:Nitroso Compounds; D010069:Oxadiazoles; D011810:Quinoxalines; D014970:Xanthines; C094210:2,2'-(hydroxynitrosohydrazono)bis-ethanamine; D019820:Xanthine; D010656:Phenylephrine; D009569:Nitric Oxide; C037047:manganese GTP; D006160:Guanosine Triphosphate; D014969:Xanthine Oxidase; D005996:Nitroglycerin; D006152:Cyclic GMP