title: Thiol oxidation inhibits nitric oxide-mediated pulmonary artery relaxation and guanylate cyclase stimulation.
abstract: The mechanisms through which thiol oxidation and cellular redox influence the regulation of soluble guanylate cyclase (sGC) are poorly understood. This study investigated whether promoting thiol oxidation via inhibition of NADPH generation by the pentose phosphate pathway (PPP) with 1 mM 6-aminonicotinamide (6-AN) or the thiol oxidant diamide (1 mM) alters sGC activity and cGMP-associated relaxation to nitric oxide (NO) donors [S-nitroso-N-acetylpenicillamine (SNAP) and spermine-NONOate]. Diamide and 6-AN inhibited NO-elicited relaxation of endothelium-denuded bovine pulmonary arteries (BPA) and stimulation of sGC activity in BPA homogenates. Treatment of BPA with the thiol reductant DTT (1 mM) reversed inhibition of NO-mediated relaxation and sGC stimulation by 6-AN. The increase in cGMP protein kinase-associated phosphorylation of vasodilator-stimulated phosphoprotein on Ser239 elicited by 10 microM SNAP was also inhibited by diamide. Activation of sGC by SNAP was attenuated by low micromolar concentrations of GSSG in concentrated, but not dilute, homogenates of BPA, suggesting that an enzymatic process contributes to the actions of GSSG. Relaxation to agents that function through cAMP (forskolin and isoproterenol) was not altered by inhibition of the pentose phosphate pathway or diamide. Thus a thiol oxidation mechanism controlled by the regulation of thiol redox by NADPH generated via the pentose phosphate pathway appears to inhibit sGC activation and cGMP-mediated relaxation by NO in a manner consistent with its function as an important physiological redox-mediated regulator of vascular function.
authors.affiliation: Dept. of Physiology, New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Mingone
authors.forename: Sachin A
authors.initials: SA
authors.lastname: Gupte
authors.forename: Noorjahan
authors.initials: N
authors.lastname: Ali
authors.forename: Richard A
authors.initials: RA
authors.lastname: Oeckler
authors.forename: Michael S
authors.initials: MS
authors.lastname: Wolin
mesh_terms: D000818:Animals; D002417:Cattle; D006152:Cyclic GMP / Q000378:metabolism; D004790:Enzyme Induction; D006162:Guanylate Cyclase / Q000378:metabolism*; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009126:Muscle Relaxation / Q000187:drug effects*; D009249:NADP / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010084:Oxidation-Reduction; D010427:Pentose Phosphate Pathway; D010766:Phosphorylation; D011651:Pulmonary Artery / Q000187:drug effects* / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014664:Vasodilation / Q000502:physiology; D014665:Vasodilator Agents
chemical_list: D020030:Nitric Oxide Donors; D013438:Sulfhydryl Compounds; D014665:Vasodilator Agents; D009569:Nitric Oxide; D009249:NADP; D006162:Guanylate Cyclase; D006152:Cyclic GMP