Pudendal denervation affects the structure and function of the striated, urethral sphincter in female rats.

Our aim was to examine the effects of denervation on urethral anatomy and urine voiding pattern. Rats usually void at one end of their cage, which gives a behavioral index of continence. The voiding preference for denervated rats was decreased to 88.8 + 4.7%, n = 32, P < 0.001, compared to improvements with time for unoperated (117 +/- 10%, n = 16) or sham-operated rats (105 +/- 8%, n = 5). The volume of urine or the frequency of voidings between denervated, unoperated or sham-operated rats did not differ significantly. Urethral sections were analyzed immunochemically and quantified morphometrically. Smooth muscle volume remained constant but skeletal muscle volume decreased after denervation, from 43 +/- 2% to 36 +/- 3% (P < 0.05, n = 5). Fiber diameter decreased from 14.3 +/- 1.4 microm to 8.5 +/- 0.7 microm (P < 0.005). We concluded that pudendal nerve transection in female rats causes behavioral alterations in voiding and muscular atrophy of the striated sphincter.