EXPERIMENTAL STUDY ON THE MICTURITION MECHANISM

The Role of the Pudendal Nerve on the Dynamics of Micturition in the Decerebrated Dog

Abstract

The present study was designed to clarify the role of the pudendal nerve in the dynamics of micturition in the dog. The voiding cycle was studied by measuring the bladder pressure, urinary flow, sphincter EMG, before and after pudendal nerve transection in 16 decebrated dogs.
The bladder pressure was monitored via a catheter inserted into the bladder, which was connected to a pressure transducer. The urine flow was measured by an electromagnetic flowmeter attached to the external urethral meatus. The EMG of the sphincter was recorded by a needle electrode.
In the control conditions, highly reproducible reflex micturition was demonstrated. Bladder contraction and spasmodic contraction of the sphincter play an important role in bladder emptying, however bladder emptying is incomplete generally. The patterns of micturition after pudenal nerve transection were divided into three groups as follows. In 9 out of the 16 dogs, reflex micturition was developed after bilateral pudendal nerve transection. In 5 out of the 16 dogs, overflow incontinence was revealed after bilateral pudendal nerve transection. In 2 out of the 16 dogs overflow incontinence was present after unilateral pudendal nerve trasection. Furthermore, after pudendal nerve trasection, the spasmodic contraction of the sphincter was diminished to decrease the efficacy of the bladder emptying.
It appears that pudendal nerve induces the spasmodic contraction of the sphincter which is neccessary for bladder emptying in decerebrated dogs.