Changes in angiotensin II type 1 receptor expression in the rat bladder by bladder outlet obstruction.

PURPOSE To demonstrate the change in the expression of angiotensin II type 1 receptor (AT1) in the rat bladder with partial bladder outlet obstruction (P-BOO). MATERIALS AND METHODS Bladder specimens were obtained from 12-week-old Wistar female rats that were divided into two groups, a P-BOO group and a control group. The rats of the P-BOO group were divided into six groups: a sham-operated control group, 1 day postoperatively, 2 days postoperatively, 4 days postoperatively, 7 days postoperatively and 14 days postoperatively. The cystometric findings and immunohistochemical staining of the detrusor muscle with the AT1 antibody were compared in each group. RESULTS AT1 localized on the cell membrane of the detrusor smooth muscle and in cytoplasm of suburothelial myofibroblasts in the control rats. The expression of AT1 disappeared in the detrusor muscle and suburothelial myofibroblasts in P-BOO, but AT1 was highly expressed in urothelial cells 1 day after surgery. The expression of AT1 in urothelial cells gradually decreased with time after surgery. AT1 completely disappeared in urothelial cells 14 days after surgery. CONCLUSIONS The present study demonstrated that the site of AT1 expression changes in response to the mechanical stress caused by P-BOO, and finally there was no expression of AT1 in rat bladder tissue following P-BOO. These data suggest the change in AT1 expression may play a role in bladder function.