DENERVATION SUPERSENSITIVITY OF THE URETHRA OF THE CHRONIC NEUROGENIC BLADDER

A Pharmacologic Evidence for the Predominant Influence of α-Adrenergic System in the Sphincteric Urethra

Abstract

The response of the urethra to various autonomic stimulants was investigated in 39 individuals whose urethra were either structurally or innervatorily variable. Only the urethra of the chronically denervated bladder responded to α-stimulation with a uniform supersensitivity of 10mmHg or more of the rise above the control in urethral pressure. This supersensitivity to α-stimulation was abolished by preliminary administration of regitine, while it was not affected by either arfonad or buscopana. Supersensitivity to cholinergic stimulation seen in a few instances appears to be a result of its weak nicotinic action on the intramural ganglia whereby catecholamine was liberated via the short adrenergic system and effected on the α-receptor, because preliminary administration of regitine or arfonad and not buscopan abolished this response. These appear to afford substantial neuropharmacological evidence to the recently evolving concept of peculiar innervatory pattern of the urinary sympathetic system where it is characterized by 1) duality with parasympathetic system, 2) intrinsic short neuron system and 3) a system of modulating parasympathetic postganglionic synapse in relation to the short neuron, and to the significant contribution of α-adrenergics to the function of the urethra inclusive of the rhabdosphincter. The mechanism of the supersensitivity was speculated.