Effect of sildenafil citrate on penile weight and physiology of cavernous smooth muscle in a post-radical prostatectomy model of erectile dysfunction in rats.

Objectives: To evaluate the gross morphometric changes and in vitro responses of the corpus cavernosus of rats treated with sildenafil citrate after cavernous neurotomy.

Methods: The animals were divided into 3 groups. Group 1 consisted of sham-operated rats (n = 16); group 2 consisted of rats that underwent bilateral cavernous neurotomy (BCN) (n = 16); and group 3 consisted of rats that underwent unilateral cavernous neurotomy (UCN) (n = 16). Each group of rats was further classified into 2 subgroups according to whether or not they received sildenafil treatment. The rats were killed on postoperative day 14, and penectomy was performed. Apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL), and organ-bath studies were evaluated by Phenylephrine (Phe), acetylcholine (Ach), sodium nitroprusside (SNP), and electrical field stimulation (EFS) responses.

Results: Penile weight in the BCN group was significantly lower than that of sham-treated group. UCN allowed much more preservation of penile weight compared with that in the sham-treated group. Sildenafil citrate treatment had positive effects on penile weight of both BCN (P = .003) and UCN (P = .004) groups. BCN increased smooth muscle apoptosis when compared with the sham or UCN group. Sildenafil citrate had a positive effect on the apoptotic index. In the BCN group, responses to Phe, Ach, SNP, and EFS decreased significantly, and sildenafil treatment corrected the responses to Phe, Ach, and SNP.

Conclusions: Our experimental study results support that early and daily sildenafil citrate treatment has a protective affect on the adrenergic and cholinergic systems, which play a role in erectile function.