STUDIES OF URODYNAMICS

6: A Neuropharmacological Study of the Urethral Pressure Profile

Abstract

The study was performed to compare the contributions of sympathetic, parasympathetic and somatic innervation on the urethra to the urethral pressure profiles of 20 female mongrel dogs with an average weight of 12.6kg (range: 7.0-23.0kg).
Urethral pressure profiles were measured by the method of Brown, M. and Wickham, J. E. A. (1969) under treatment of 1) bilateral transection of pudendal and hypogastric nerves and 2) intravenous administration of phentolamine mesylate, atropine sulfate and succinylcholine chloride. Prior to treatment, a serial 9-time-measurement of urethral pressure profiles revealed a satisfactory reproducibility of this method. The results of this study are as follows.
1. Somatic component contributes to about 50 per cent of the static urethral pressure and its location is mainly in the distal four fifths of the urethra.
2. Sympathetic component contributes to about 40 per cent of the static urethral pressure and its location is mainly in the proximal four fifths of the urethra.
3. These two components overlap each other in the midurethra and the urethral pressure consists of somatic, sympathetic and non-neural components.
4. Parasympathetic nerves contribute little to static urethral pressure.
5. It is suggested that some sympathetic nerve pathways different from the hypogastric nerve or a mechanism which makes up for the loss of pressure due to hypogastric nerve section may exist in the urethra.