Changes in Aquaporin 1 Expression in Rat Urinary Bladder after Partial Bladder Outlet Obstruction: Preliminary Report

PURPOSE Aquaporins (AQPs) are membrane proteins that facilitate water movement across biological membranes. AQPs are also called water channels, and they have recently been reported to be expressed in rat and human urothelium. The purposes of this study were to investigate the effect of bladder outlet obstruction (BOO) on the rat urothelium and AQP1 expression in rat urothelium. MATERIALS AND METHODS Female Sprague-Dawley rats (230-240 g each, n=20) were divided into 2 groups: the sham group (the Con group, n=10) and the partial BOO group (the BOO group, n=10). The BOO group underwent a partial BOO. The expression and cellular localization of AQP1 were determined by performing Western blotting and immunohistochemistry on the rat urinary bladder. RESULTS AQP1 immunoreactivity in both the control and the BOO groups was localized in the capillaries, arterioles, and venules of the lamina propria of the urinary bladder. The protein expression of AQP1 was significantly increased in the BOO group. CONCLUSIONS This study showed that BOO causes a significant increase in the expression of AQP1. This may imply that AQP1 has a functional role in the detrusor instability that occurs in association with BOO.