Anastomosis (vasovasostomy) of epididymal and prostatic halves of vasa deferentia was carried out in rats in which unilateral or bilateral medial transection (vasectomy) had been performed 4 weeks previously. 2. Noradrenaline levels in epididymal halves of vasa deferentia, 8 weeks after anastomosis with prostatic halves, were approximately 40% of those in epididymal halves of contralateral, unoperated vasa deferentia. Catecholamine fluorescence was partially restored after anastomosis. 3. Responses of epididymal halves of transected vasa deferentia to electrical field stimulation (1 ms, 60 V, 10 pulses at 0.01-50 Hz) were partially restored 8 and 15 weeks after anastomosis. 4. Noradrenaline was equipotent in causing contraction of epididymal halves of unoperated and anastomosed vasa deferentia at 8 and 15 weeks after vasovasostomy. The ability of nisoxetine (0.1 mumol/l) to potentiate the effects of noradrenaline was partially restored by vas deferens repair. 5. Noradrenaline levels and neurotransmission in prostatic halves of vasa deferentia were relatively unaffected by vasectomy and subsequent vasovasostomy. 6. Fertility was restored 4-8 weeks after bilateral anastomosis performed in a group of eight rats 4 weeks after bilateral vasectomy. 7. These observations show that in the rat the noradrenergic denervation of the epididymal segment of the vas deferens after medial transection is partially reversible by anastomosis 4 weeks later, and that full noradrenergic reinnervation of the organ is not essential for the return of fertility after vasectomy and vasovasostomy in this species.
