RT Journal Article
SR Electronic
T1 Mechanisms Underlying Activation of Soluble Guanylate Cyclase by the Nitroxyl Donor Angeli's Salt
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 1115
OP 1122
DO 10.1124/mol.109.059915
VO 76
IS 5
A1 Andreas Zeller
A1 M. Verena Wenzl
A1 Matteo Beretta
A1 Heike Stessel
A1 Michael Russwurm
A1 Doris Koesling
A1 Kurt Schmidt
A1 Bernd Mayer
YR 2009
UL http://molpharm.aspetjournals.org/content/76/5/1115.abstract
AB Nitroxyl (HNO) may be formed endogenously by uncoupled nitric-oxide (NO) synthases, enzymatic reduction of NO or as product of vascular nitroglycerin bioactivation. The established HNO donor Angeli's salt (trioxodinitrate, AS) causes cGMP-dependent vasodilation through activation of soluble guanylate cyclase (sGC). We investigated the mechanisms underlying this effect using purified sGC and cultured endothelial cells. AS (up to 0.1 mM) had no significant effect on sGC activity in the absence of superoxide dismutase (SOD) or dithiothreitol (DTT). In the presence of SOD, AS caused biphasic sGC activation (apparent EC50 ∼10 nM, maximum at 1 μM) that was accompanied by the formation of NO. DTT (2 mM) inhibited the effects of <10 μM AS but led to sGC activation and NO release at 0.1 mM AS even without SOD. AS had no effect on ferric sGC, excluding activation of the oxidized enzyme by HNO. The NO scavenger carboxy-PTIO inhibited endothelial cGMP accumulation induced by AS in the presence but not in the absence of SOD (EC50 ∼50 nM and ∼16 μM, respectively). Carboxy-PTIO (0.1 mM) inhibited the effect of ≤10 μM AS in the presence of SOD but caused NO release from 0.1 mM AS in the absence of SOD. These data indicate that AS activates sGC exclusively via NO, formed either via SOD-catalyzed oxidation of HNO or through a minor AS decomposition pathway that is unmasked in the presence of HNO scavenging thiols. © 2009 The American Society for Pharmacology and Experimental Therapeutics