SYMPATHETIC NERVOUS-SYSTEM EFFECTS ON FELINE BLADDER WALL COMPLIANCE THROUGHOUT CONTINENCE

The urinary bladder is a compliant organ, high compliance being essent ial for useful urine storage. The extent to which the sympathetic nerv ous system promotes the storage of urine by increasing bladder complia nce is unclear. The aim of the present study was to determine the rang e of bladder volumes over which the sympathetic nervous system increas ed bladder wall compliance. In supine, anaesthetized cats, the bladder was filled at twice the rate of natural filling, the continence cycle being interrupted at five stages. These stages were when the bladder had become globular, during prodromal contractions, soon after non-mic turating contractions had commenced, approximately two-thirds of the w ay through the continence cycle and just prior to micturition. During each of these interruptions, bladder volume was held constant while pe lvic nerve afferent activity and bladder pressure were recorded. Recor dings were obtained before and during the intravenous infusion of trim ethaphan, the resulting partial ganglion blockade decreasing arterial pressure by a third. Bladder pressure as well as afferent nerve activi ty increased significantly when the sympathetic drive was transiently blocked, indicating that there had been a prevailing net sympatho-inhi bitory effect promoting bladder wall relaxation. This effect was obser ved during prodromal contractions and continued until the onset of mic turition. This net sympatho-inhibitory effect is a potential therapeut ic path for the treatment of bladder storage disorders.