THE EFFECT OF SILDENAFIL ON APOMORPHINE-EVOKED INCREASES IN INTRACAVERNOUS PRESSURE IN THE AWAKE RAT

Purpose: The aim of this study was to develop a quantitative, awake animal model to investigate the effect of sildenafil on centrally-evoked erectile activity.Methods: Intracavernous pressures were recorded in awake, male Sprague Dawley rats after administration of apomorphine (100 or 250 micro g./kg. subcutaneously). Sildenafil (100 micro g./kg. intravenously) was then given 10 min. after a second dose of apomorphine. The time to first response, duration of response, and peak intracavernous pressure and area under the response, were measured before and after sildenafil.Results: Apomorphine produced rhythmic increases in intracavernous pressure. The pressure increase consisted of two components. The amplitude of the first, tonic response was 58 +/− 3 mm. Hg, and a superimposed, burst-like increase in pressure elevated this further to 81 +/− 6 mm. Hg. Bilateral transection of the pudendal nerves abolished the burstlike pressure changes; bilateral transection of the cavernous nerves prevented both r...