Анотация: The changes of contractile activity of smooth muscle strips from urinary bladder of Wistar rats induced by angiotensin II were examined. The preparations were subjected to the influence of medium containing high calcium concentration to establish the participation of extracellular calcium in smooth muscle contraction. The role of membrane calcium channels in angiotensin II-induced contraction was investigated by application of selective (1-octanol) and nonselective (nicardipine) calcium channel blockers. Angiotensin II (1 хМ) and СаCl2 (10 mМ) provoked contractile response with maximum amplitudes of 1.57+0.5 g and 1.5+0.6 g, respectively. Both types of calcium channel antagonists inhibited the contractile response of the urinary bladder detrusor. Our results showed a greater significance of calcium-induced calcium release than inositol-triphosphate-induced calcium release in tonic contraction of detrusor muscle strips