Nervous Control of Urinary Bladder in Cats

Intravesical pressure under isometric conditions was studied in anesthetized cats after operative canalization of the bladder. Records were obtained after selective transection at the peripheral and at the intraspinal level of the sympathetic and parasympathetic nerves supplying the bladder, after rhizotomy of the thoraco‐lumbar and sacral nerves to the bladder, and after transection of the spinal cord at various levels. With small bladder volumes no change in pressure was observed after the various lesions, but as the volume increased, the concomitant rise in bladder pressure was progressively inhibited by sympathetic nervous impulses. In particular was this inhibition marked during the last one‐third of the cystometrogram. The sympathetic influence is maintained by a spinal reflex with the afferent path through the posterior sacral roots, its stimulus being stretching of the bladder wall. The effect of this spinal adaptation reflex is thus to permit increasing bladder volumes with only moderate increases in bladder pressure. ‘Nonspecific’ bladder responses consisted in an increase in motility caused by the laparotomy, and an inhibition of motility caused by any intraspinal procedure. This inhibitory effect was found to be due to discharge through the sympathetic nerves on manipulation of spinal structures, regardless of their relation to the segments supplying the bladder.