Induction of penile erection by intracavernosal and transurethral administration of novel nitric oxide donors in the cat

Purpose: The effects of novel nitric oxide (NO) donors administered intracavernosally and transurethrally on erectile function in the anesthetized cat were evaluated. Materials and Methods: In pentobarbital-anesthetized cats, increases in intracavernosal pressure, penile length, and duration of erectile response were determined after intracavernosal and transurethral injections of novel NO donors (MAHMA/NO, PAPA/NO, DEA/NO, PIPERAZI/NO and PROLI/NO). All parameters were measured after administration of NO donors intracavernosally via a 30-gauge needle and urethrally via a Jelco i.v. catheter in a volume of 200 mu l. Systemic arterial pressure was also assessed in these experiments. All NO donors were compared with a triple-drug control combination comprised of papaverine (1.65 mg.), prostaglandin E-1 (0.5 mu g.), and phentolamine (25 mu g.). Results: MAHMA/NO, PAPA/NO, DEA/NO, PIPERAZI/NO and PROLI/NO induced dose dependent increases in intracavernosal pressure and penile length (p <0.05) when administered intracavernosally. The increases in cavernosal pressure and penile length were comparable to those observed with the triple-drug control combination. The maximum increase in cavernosal pressure in response to PROLI/NO and PAPA/NO was associated with no significant change in systemic arterial pressure. Transurethral administration of PROLI/NO and PIPERAZI/NO induced dose-dependent increases in cavernosal pressure and penile length (p <0.05). The response was similar to that of the triple-drug control combination, except that transurethral PROLI/NO and PIPERAZI/NO had no significant effect on systemic blood pressure. Conclusions: NO donors caused dose-dependent increases in cavernosal pressure when administered intracavernosally and transurethrally. These data suggest further exploration of the use of NO donors for the treatment of erectile dysfunction.