Rabbits as models for impotence research.

The anesthetized rabbit model is useful and has many advantages: ability to perform neurophysiological studies; more administration routes, including intracavernous injection; haemodynamic measurements in parallel to measurements of intracavernous pressure or penile volume; and direct measurement of intracavernosal pressure and blood flow. This model has been evaluated with many different types of drugs. The conscious rabbit model is a simple and valid model for the assessment of compounds with potential for treatment of ED. It offers several methodological advantages as a screening model for compounds with erection stimulating properties. It was clearly successful in demonstrating the efficacy and the mechanism of the new potent and selective PDE5 inhibitor vardenafil. The model was also effective in demonstrating erection-generating properties through other mechanisms, eg PDE3 inhibitors and alpha-receptor blockers. In conclusion, both anaesthetized rabbit model and the newly developed conscious-rabbit models are well-suited for studies in impotence research.