Effects of exogenous testosterone on isolated rabbit corpus cavernosum penis

AIM: To study the effects of exogenous excess of testosterone on the constr icting effect of phenylephrine and endothelium-dependent and -independent r elaxing effects of different:agonists in the corpus cavernosum penis (CCP). METHODS: Specimens of the CCP were obtained from rabbits testosterone for 1 and 2 months and untreated for 2 months after testosterone-treatment for 2 months. Preparations were mounted between two parallel platinum electrode s in organ baths. Responses to phenylephrine, car bachol, and:sodium nitrop russide were obtained by adding the reagent cumulatively to the bath. RESUL TS: The phenylephrine-induced contractions were decreased with no change in agonist potency (pD(2) value) after both 1 and 2 month testosterone-treatm ent and did not return to control: values in corpus cavernosum obtained fro m rabbits untreated for 2:months after testosterone-treatment for 2 months. Testosterone treatment for 1 or 2 months increased the endothelium-depende nt relaxations induced by carbachol and decreased the relaxations elicited by electric stimulation but did not affect the relaxations induced by sodiu m nitroprusside. These relaxant responses to carbachol and electric stimula tion did not return to control values in corpus cavernosum obtained from ra bbits untreated for 2 months after testosterone-treatment for 2 months. The re were no significant changes in the pD(2) values calculated:by agonist-in duced relaxation responses in all tesrosterone-treatment.