Sildenafil citrate on nitrergic transmission in anococcygeus muscles from the urogenital system of male and female mice

The effects of sildenafil on nitrergic relaxations were compared in anococcygeus muscles from male and female mice. In muscles from both sexes, sildenafil (10-300 nM) produced a weak, direct relaxation of carbachol-induced tone, and increased both the amplitude and duration of nitrergic relaxations. The most marked effect was on nitrergic duration (300-400% increase with 300 nM sildenafil); no differences in potency were observed between male (EC50, 30 nM) and female (EC50, 25 nM). The rate of onset for potentiation of nitrergic duration was similar in both sexes; but, on washout, the effects of sildenafil declined more slowly in the male muscle. Relaxations to both nitric oxide (NO) and sodium nitroprusside were also increased in amplitude and duration by 50 nM sildenafil, while those to forskolin and papaverine were unaffected. The results demonstrate that sildenafil causes a similar, potent and selective potentiation of nitrergic transmission in urogenital smooth muscle from both male and female mice. (C) 2000 Elsevier Science B.V. All rights reserved.