Effects of in vivo Ischemia on the infusion cystometry and in vitro whole bladder contractility of the rat.

Ischemia induced by atherosclerosis is a common cause of organ failure in the elderly. We investigated the effects of in vivo ischemia created by ligation of the internal iliac arteries on the parameters of in vivo infusion cystometry under urethane anesthesia and on in vitro whole bladder contractility of the rat. Bladder weight significantly increased after ischemia for 14 days. Infusion cystometry demonstrated that in the ischemic bladders the capacity increased, the voiding pressure decreased, and the volume of residual urine increased, which resulted in deteriorated voiding efficacy. The in vitro whole bladder contractility to field stimulation, bethanechol, ATP, and KCl was reduced by ischemia. The passive pressure increased as the bladder volume enlarged and the bladder compliance once decreased by ischemia on the 7th day, but increased on the 14th day. In an active volume-pressure relationship study the peak response was decreased by ischemia. The volume at which response reached a peak value shifted to a larger volume 14 days after surgery. In conclusion, ischemia impaired in vivo rat detrusor power to empty. Since detrusor contractility in vitro decreased in response to various kinds of stimulation, this deteriorated bladder function was supposed to be caused by muscle degeneration.