[Urethral response to sympathetic nerve stimulation in the cat].

The responses of the urethra to hypogastric nerve (HGN) and lumbosacral sympathetic chain (SC) stimulation were observed in 25 chloralose-anesthetized cats. Urethral perfusion pressure was monitored as an index of functional urethral responses. SC was stimulated at four points from L4 to S1. Urethral constrictive response induced by HGN stimulation (delta P:HGN) was significantly larger in male cats than in female cats. But there was no difference between male and female cats in urethral constrictive response induced by SC stimulation (delta P:SC). delta P:HGN was significantly larger than delta P:SC in both sexes, and the ratio of delta P:HGN to delta P:SC (L7-S1) was 2.7 to 1 in male cats and 1.7 to 1 in female cats. delta P:HGN was blocked by the alpha-adrenergic antagonist phentolamine (1-2 mg/kg) and reduced about 50% by autonomic ganglion blockade with hexamethonium bromide (2 mg/min, 25-50 mg). delta P:SC was blocked by both phenotolamine and hexamethonium bromide. In order to examine the pathways of projections of sympathetic fibers from the sacral SC to the urethra, HGN, pelvic nerve and pudendal nerve were transected serially. delta P:SC (L7-S1) was decreased 0%, 12% and 50% by transection of HGN, pelvic nerve and pudendal nerve, respectively. After severance of these three nerves, delta P:SC (L7-S1) was reduced 62%, but not abolished. These data suggest: 1) The effect of HGN to the feline urethra is more prominent than that of SC in both sexes and significantly larger response was noted in male cats with HGN stimulation but not with SC.(ABSTRACT TRUNCATED AT 250 WORDS)