Effects of Silodosin, a Selective α1A-Adrenoceptor Antagonist, on Bladder Blood Flow and Bladder Function in a Rat Model of Atherosclerosis Induced Chronic Bladder Ischemia without Bladder Outlet Obstruction

Purpose: We investigated the effects of the selective alpha(1A)-adrenoceptor antagonist silodosin on bladder blood flow and bladder function in a rat model of atherosclerosis induced chronic bladder ischemia without bladder outlet obstruction. Materials and Methods: The chronic bladder ischemia model was prepared by creating balloon endothelial injury of the bilateral iliac arteries in male rats. Using an osmotic pump, chronic bladder ischemia rats received silodosin subcutaneously at a rate of 0.1 or 0.3 mg/kg per day, or vehicle for 8 weeks. All groups received a 2% cholesterol diet throughout the experiment. For each alpha(1)-adrenoceptor subtype mRNA expression in bladder microvessels was examined by in situ hybridization. Bladder blood flow was measured using a laser speckle blood flow imager. Malondialdehyde in bladder tissue and 8-hydroxy-2'-deoxyguanosine in urine were measured as markers of oxidative stress. A metabolic cage study and cystometry were performed in conscious rats. Results: The expression of all alpha(1)-adrenoceptor subtype mRNA was observed in rat bladder microvessels. Silodosin abrogated the decreased bladder blood flow in the empty bladder and during bladder distention that were evident in rats with chronic bladder ischemia. Levels of oxidative stress markers in these rats were significantly decreased by silodosin administration. Silodosin ameliorated bladder dysfunction in rats with chronic bladder ischemia in the metabolic cage study and on cystometry. Conclusions: Results suggest that in ischemic conditions alpha(1)-adrenoceptor antagonists such as silodosin may improve bladder function by restoring bladder blood flow.