THE EFFECT OF AUTONOMIC ANTAGONISIS ON THE IN VIVO URETHRA IN THE FEMALE DOG

Abstract

Urethral action to electrical hypogastric and pelvic nerve stimulations in the proximal urethra of the female dog was examined in control conditions and after administration of five autonomic blocking agents to investigate the effect of autonomic antagonists on the proximal urethra. Autonomic antagonists administered intraarterially and the response of the in vivo urethra was studied by measurements of motility and pressure changes.
In the control condition, hypogastric nerve stimulation produced a monophasic contractile response in the urethra, and pelvic nerve stimulation produced a variable and complicated response in the urethra.
Proximal urethral responses to hypogastric nerve stimulation were blocked by administration of phentolamine and guanethidine, increased by propranolol, and not influenced by hexamethonium and atropine. These responses seem to be mediated through the long postganglionic adrenergic fibers which arise from the inferior mesenteric ganglia.
Proximal urethral responses to pelvic nerve stimulation were blocked by administration of phentolamine, guanethidine, hexamethonium and atropine, and not influenced by propranolol.
The mechanism of the inhibition of the pelvic nerve responses by phentolamine and guanethidine remained unknown. The present study strongly suggests the importance of adrenergic action on the lower urinary tract function.