Role of supraspinal alpha 1-adrenoceptors for voiding in conscious rats with and without bladder outlet obstruction

Purpose: Previous studies have shown that spinal alpha1-adrenoceptors can influence voiding in normal rats and in rats with outlet obstruction. Also, at the supraspinal level such receptors may be involved in voiding control. Therefore, we studied in rats the effects on cystometrography of intracerebroventricular administered alpha1-adrenoceptor antagonists. Materials and Methods: Continuous cystometry was performed in conscious, freely moving rats with and without bladder outlet obstruction. Cystometric parameters were evaluated before and after intracerebroventricular drug administration. Results: In normal rats intracerebroventricular administration of 8 nmol. kg.(-1) prazosin (Pfizer Central Research, Sandwich, United Kingdom) or terazosin (Abbott Laboratories, Abbott Park, Illinois) (nonsubtype selective) caused no change in cystometric parameters. At 24 or 80 nmol. kg.(-1) the 2 drugs significantly decreased voiding pressure and increased bladder capacity, voided volume and post-void residual urine volume. Administering vehicle had no effect. In rats with outlet obstruction the drug effects were significantly more pronounced than in normal animals (p