THE RABBIT AS AN INTRACAVERNOUS INJECTION STUDY MODEL

We investigated the feasibility of using the rabbit as an animal model for intracavernous injection studies. The rabbit, having a penile str ucture rather similar to that of humans, offers the advantage of being a strain-specific, adequately sized, and easily controlled experiment al animal. Using intracavernous injections of the two vasoactive drugs prostaglandin E(1) (PGE(1), 0.2-1.6 mu g/kg) and papaverine (PAP, 0.2 5-1 mg/kg), which have been commonly used in the management of erectil e dysfunction in man, increases intracavernous pressure (Delta ICP) we re induced. After intracavernous injection of PCE(1), the maximal Delt a ICP ranged from 18 to 44 mmHg (mean 29.25 +/- 7.85 mmHg) with a dura tion of tumescence from 3.1 to 13.3 min (mean 8.61 +/- 3.71 min). Intr acavernous injection of PAP also induced increases in ICP, with a maxi mal Delta ICP ranging from 24 to 56 mmHg (mean 43.5 +/- 11.35 mmHg) an d a duration of tumescence from 5.3 to 15 min (mean 10.25 +/- 3.39 min ). The systemic blood pressures were unchanged after all intracavernou s injections. In addition, administration of cAMP antagonist in combin ation with PGE(1) inhibited the relaxing effects of PGE(1) in a dose-d ependent manner. Our results suggest that the effects of vasoactive dr ugs on the rabbit's corpus cavernosum are similar to those in humans; thus the rabbit model is a suitable alternative for further physiologi cal and pharmacological studies of penile erection.