Erectile response to acute and chronic occlusion of the internal pudendal and penile arteries

We designed two animal experiments to elucidate the effect of obstruction of the internal pudendal artery on erectile function. In five dogs the internal pudendal or penile artery was acutely clamped unilaterally or bilaterally with a non-crushing vascular clamp. In eight dogs, the internal pudendal or penile artery was ligated, unilaterally or bilaterally, and occlusion was maintained for two months. In both models, electrodes were implanted around the cavernous nerves for electroerection. In unilateral occlusion, blood flow in the contralateral internal pudendal artery was recorded via an ultrasonic probe. In both unilateral and bilateral occlusion, intracavernous pressure in both corpora cavernosa was recorded through a 21-gauge butterfly needle connected to a Statham transducer. In the chronic model, selective pudendal angiography was done after the erection study was completed; the dogs were then sacrificed and the penile tissue was examined histologically under light microscopy. Unilateral acute clamping of the internal pudendal or penile artery caused a compensatory increase in arterial flow in the contralateral pudendal artery with only moderate impairment of intracavernous pressure on the ipsilateral side, but bilateral occlusion resulted in a marked reduction in the intracavernous pressure response to neurostimulation. In contrast, chronic obstruction of penile vessels had a minimal effect on erectile function due to the development of a rich network of collaterals around the penis. Histological evaluation revealed mild local changes in the cavernous tissue with characteristic compensatory enlargement of branches of the cavernous artery on the control side in cases of unilateral occlusion.