Experimental studies on sympathetic innervation of lower urinary tract. Quantitation of nerve terminals and urethral pressure response after hypogastric denervation

Abstract

On 6 female mongrel dogs (denervated group), bilateral hypogastric nerves were cut distally to the inferior mesenteric ganglion. Five dogs were kept intact as a control group. After 2-5 months, urethral pressure response to continuous noradrenaline infusion (0.1 microgram/kg/min) was monitored. The urethral pressure rose significantly after noradrenaline loading in each group, however there was no significant difference in the degree of the response between the denervated group and control group. Subsequently, the bladder and the urethra were extirpated to determine the intrinsic noradrenaline content. The tissue noradrenaline concentration was highest in the posterior urethra, intermediate in the bladder base and lowest in the bladder dome. Although these values tended to be lower in the denervated group than in the control group, no significant difference was obtained between the groups in each portion. These results suggest that the majority of sympathetic components which consists in the hypogastric nerve may involve short adrenergic neurons. Thus, chronic hypogastric denervation alone does not induce sympathetic denervation supersensitivity. Simultaneous decentralization of the pelvic nerve may be necessary for inducing sympathetic denervation supersensitivity.