Effect of acute complete obstruction on the rabbit urinary bladder.

Studies on the effect of partial bladder outlet obstruction demonstrate that significant alterations in urinary bladder structure and function occur within 24 hours of the creation of the obstruction. These studies suggest that many of the functional and structural alterations following partial outlet obstruction may result from the initial overdistension which occurs within the first 24 hours. In these present studies, we investigated the time course of the effect of complete obstruction of the rabbit urinary bladder on the contractile response to bethanechol and field stimulation and on the muscarinic receptor density. Male White New Zealand rabbits were divided into five groups: controls, four, eight, 20, and 24 hours of complete obstruction. The results demonstrated that there was a significant decrease in both the contractile response to muscarinic stimulation and muscarinic receptor density at four hours following outlet obstruction (at a time when there was no bladder overdistension). The receptor density and contractile response to stimulation further decreased over the 24 hour period. These studies indicate that the initial decrease in muscarinic receptor density and contractile response to muscarinic stimulation may be mediated in part by the high level of spontaneous contractile activity induced by ligation of the urethra.