Comparison of the effects of nifedipine on ureter and coronary artery isolated from the dog.

The effect of nifedipine (Adalat) on isolated dog ureter was compared with that on isolated coronary artery. Nifedipine at a concentration of 10(-8) mol/l significantly decreased the frequency of ureteral rhythmic contractions evoked by potassium, and suppressed the force of these contractions at a concentration of 3 X 10(-8) mol/l. In potassium-contracted coronary artery strips, nifedipine at concentrations more than 3 X 10(-9) mol/l produced significant relaxations in a concentration-dependent manner. The results indicate that nifedipine is able to act inhibitorily on ureteral contractions, and inhibition of pace making activities in ureteral smooth muscle was suggested as a mode of action of nifedipine.