Sildenafil relaxes rabbit clitoral corpus cavernosum

The role of phosphodiesterase type 5 inhibition in the modulation of female sexual dysfunction was investigated by assessing its effects on in vitro relaxation of rabbit clitoris. Stimulation of the non-adrenergic, non-cholinergic neurons of the clitorus elicited a frequency-dependent relaxation response. Inhibition of NO synthase with L-NAME (100 microM) or inhibition of soluble guanylate cyclase with ODQ (1.0 microM) almost completely abolished the electrical field stimulation-induced relaxation of clitorus suggesting that NO-cGMP pathway mediates the relaxation response to electrical field stimulation. Similarly, tetrodotoxin, a neuronal sodium channel blocker abolished the electrical field stimulation-induced clitoral relaxation implying a neuronal release of NO contributes to the electrical field stimulation elicited relaxation. Pretreatment of the clitoral corpus cavernosum strips with sildenafil (100 nM) enhanced the electrical field stimulation-induced relaxations both in magnitude and duration. The results suggest that sildenafil enhances electrical field stimulation elicited clitoral relaxation by a NO-cGMP dependent pathway. These data also imply that sildenafil may be useful to treat female sexual dysfunction.