[Mode of inhibitory action of propiverine hydrochloride on the micturition movements of the bladder in dogs].

Propiverine hydrochloride (P-4) is a new derivative of benzilic acid. The effect of P-4 on the vesico-detrusor reflex (corresponding to the first reflex of Barrington) in anesthetized or decerebrated dogs was studied to elucidate the mode of action of the drug. When bladder contraction was induced by electrical stimulation of the distal ending of the pelvic nerve under the bilateral pelvic nerve and hypogastric nerve transection, P-4 (2, 5 and 10 mg/kg, i.v.) significantly inhibited the contraction. A similar effect was also observed following intravenous administration of flavoxate (10 and 20 mg/kg), verapamil (1 mg/kg) or propantheline (2 mg/kg), while thiopental (4 mg/kg, i.v.) had no significant effect. When the bladder was filled under the bilateral pelvic nerve and hypogastric nerve transection, an increase of afferent impulses from the distal ending of a pelvic vesical branch was observed. P-4 (10 mg/kg, i.v.) had no effect on the afferent impulses. When the central endings of the pelvic vesical branches were electrically stimulated, reflex discharges were noted from a pelvic vesical branch on the contralateral side. Thiopental (2 and 4 mg/kg, i.v.) markedly decreased the reflex discharge, whereas P-4 (10 mg/kg, i.v.) caused no such inhibition. These findings suggest that the inhibition of the vesico-detrusor reflex by P-4 may result from its inhibitory action on the efferent terminal of the pelvic nerve.