title: Molecular mechanisms underlying rat mesenteric artery vasorelaxation induced by the nitric oxide-independent soluble guanylyl cyclase stimulators BAY 41-2272 [5-cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]pyrimidin-4-ylamine] and YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzyl Indazole].
abstract: The aim of this study was to investigate the mechanisms of relaxation to the nitric oxide (NO)-independent soluble guanylyl cyclase (sGC) stimulators 5-cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]pyrimidin-4-ylamine (BAY 41-2272) and 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1) in the rat mesenteric artery. In endothelium-intact rings, BAY 41-2272 (0.0001-1 microM) and YC-1 (0.001-30 microM) caused concentration-dependent relaxations (pEC(50) values of 8.21 +/- 0.05 and 6.75 +/- 0.06, respectively), which were shifted to the right by 6-fold in denuded rings. The sGC inhibitor H-[1,2,4]oxadiazolo [4,3,-a]quinoxalin-1-one (ODQ) (10 microM) partially attenuated the maximal responses to BAY 41-2272 and YC-1 and displaced their curves to the right by 9- to 10-fold in intact and 3-fold in denuded vessels. The NO synthesis inhibitor N(omega)-nitro-L-arginine methyl ester (100 microM) and the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (100 microM) reduced BAY 41-2272 and YC-1 relaxations, whereas the phosphodiesterase type 5 inhibitor sildenafil (0.1 microM) potentiated these responses. The phosphatase inhibitor calyculin A (50 nM) reduced the relaxant responses, and high concentrations of BAY 41-2272 (1 micorM) and YC-1 (10 microM) inhibited Ca(2+)-induced contractions in K(+)-depolarized rings. BAY 41-2272 (0.1 microM) and YC-1 (1 microM) markedly elevated cGMP levels in an ODQ-sensitive manner. Coincubation of BAY 41-2272 or YC-1 with a NO donor resulted in a synergistic inhibition of phenylephrine-induced contractions paralleled by marked increases in cGMP levels. In conclusion, BAY 41-2272 and YC-1 relax the mesenteric artery through cGMP-dependent and -independent mechanisms, including blockade of Ca(2+) influx. The synergistic responses probably reflect the direct effects of NO and NO-independent sGC stimulators on the enzyme, thus representing a potential therapeutic effect by permitting reductions of nitrovasodilator dose.
authors.affiliation: Department of Physiology, Medical College of Georgia, Augusta, 30912-3000, USA. cteixeira@mail.mcg.edu
authors.forename: Cleber E
authors.initials: CE
authors.lastname: Teixeira
authors.forename: Fernanda B M
authors.initials: FB
authors.lastname: Priviero
authors.forename: R Clinton
authors.initials: RC
authors.lastname: Webb
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000494:pharmacology*; D006162:Guanylate Cyclase / Q000378:metabolism*; D066298:In Vitro Techniques; D007191:Indazoles / Q000494:pharmacology; D008297:Male; D017538:Mesenteric Artery, Superior / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D011720:Pyrazoles / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014664:Vasodilation / Q000187:drug effects*
chemical_list: C423582:3-(4-Amino-5-cyclopropylpyrimidine-2-yl)-1-(2-fluorobenzyl)-1H-pyrazolo(3,4-b)pyridine; D020536:Enzyme Activators; D007191:Indazoles; D011720:Pyrazoles; D011725:Pyridines; C090937:3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole; D009569:Nitric Oxide; D006162:Guanylate Cyclase