YC-1 potentiates the nitric oxide/cyclic GMP pathway in corpus cavernosum and facilitates penile erection in rats

The aim of present study was to characterize the in vitro and in vivo pharmacological effects of YC-1 (3-(5'-hydroxymethyl-2'-furyl)-1benzyl indazole), a soluble guanylate cyclase activator, on corpus cavernosal smooth muscle and penile erectile activity. YC-1 relaxed phenylephrine precontracted cavernosal smooth muscle (EC50=4.4 muM) and this effect was partially antagonized by 1H-[1,2,4]oxadiazole [4,3-a]quinoxalin-1-one (ODQ). ODQ is a selective soluble guanylate cyclase inhibitor that completely blocked the relaxation induced by sodium nitroprusside, suggesting that YC-1 binds to soluble guanylate cyclase at a different site from nitric oxide (NO). Both YC-1 and sodium nitroprusside, but not sildenafil (1-100 muM) caused concentration-dependent increases in cyclic GMP levels in cultured rabbit cavemosal smooth muscle cells and produced synergistic effects. Intraperitoneal administration of YC-1 (10 mumol/kg) evoked penile erection in rats with 70% incidence. More importantly, YC-1 was able to significantly augment the pro-erectile effects of a suboptimal dose of apomorphine. These results suggest that the soluble guanylate cyclase activator YC-1 increases cyclic GMP levels, leading to relaxation of cavemosal smooth muscle. These biochemical events may be related to the pro-erectile properties of YC-1 in vivo. (C) 2002 Elsevier Science B.V. All rights reserved.