EFFECTS OF SPINAL ALPHA(1)-ADRENOCEPTOR ANTAGONISM ON BLADDER ACTIVITY-INDUCED BY APOMORPHINE IN CONSCIOUS RATS WITH AND WITHOUT BLADDER OUTLET OBSTRUCTION

To test the hypothesis that the spinal control of micturition involves alpha(1)-adrenoceptors, the urodynamic effects of intrathecal and int raarterial alpha(1)-adrenoceptor blockade on apomorphine-induced bladd er activity in rats were studied. Continuous cystometry was performed in conscious female Sprague-Dawley rats with and without bladder outfl ow obstruction. In normal rats, subcutaneous apomorphine, 30 mu g/kg, induced bladder activity that was abolished or attenuated by the alpha (1)-adrenoceptor antagonists indoramin and doxazosin given intrathecal ly or intra-arterially. In rats with outlet obstruction, apomorphine 3 0 mu g/kg caused no change in cystometric parameters. However, at a do se of 100 mu g/kg the drug induced bladder activity, which was attenua ted by intrathecal indoramin or doxazosin. These results suggest that the bladder activity evoked by apomorphine-stimulation of bulbospinal pathways can be influenced by alpha(1)-adrenoceptors at the spinal and peripheral levels, both in normal rats and in rats with bladder hyper trophy secondary to outlet obstruction. (C) 1997 Wiley-Liss, Inc.