ROLE OF SYMPATHETIC INNERVATION IN THE FELINE CONTINENCE PROCESS UNDER NATURAL FILLING CONDITIONS

1. The effect of the sympathetic innervation on the bladder detrusor muscle was assessed in pentobarbitone-anesthetized cats by measuring the changes in bladder wall tension that occurred during sympathetic ganglion blockade after filling the bladder at a natural rate. 2. At a point 60% of the way through the continence process, systemic sympathetic blockade was produced by intravenous trimethaphan, and selective blockade of postganglionic hypogastric nerve activity was produced by application of trimethaphan to the exposed inferior mesenteric ganglia. The level of blockade was monitored with an in-continuity hypogastric nerve recording. 3. During both systemic and selective ganglion blockade, there was an increase in baseline transmural bladder pressure and a decrease in the amplitude of nonmicturating contractions. 4. Although there was no change in the mean level of transmural bladder pressure during either systemic or selective blockade, there was a significant increase in the mean level of bladder wall mechanoreceptor discharge, suggesting that before the blockade sympathoinhibitory effects were greater than sympathoexcitatory effects. 5. Measurement of bladder wall mechanoreceptor discharge before and during ganglion blockade revealed a net sympathoinhibitory influence on the level of bladder wall tension under natural filling conditions. These results confirm that the detrusor muscle of the feline bladder is under both sympathoinhibitory and sympathoexcitatory influences for a significant portion of the continence process.