Inhibition by Benidipine of Contractility of Isolated Proximal and Distal Caprine Ureter

CONTEXT: Benidipine is a calcium channel blocker that blocks all the major types (L, N, and T) of calcium channels. It has been shown to inhibit the contractility of many isolated smooth muscles but not isolated ureter. AIMS: This study evaluated the ability of benidipine to inhibit the spontaneous contractility of isolated proximal and distal caprine (goat) ureter. SETTINGS AND DESIGN: Spontaneous contractility of isolated goat ureter was recorded using a physiograph. MATERIALS AND METHODS: Benidipine at concentrations in the range of 1 nM to 10 μM was analyzed for its inhibitory effects on the spontaneous contractility of the isolated proximal and distal caprine ureter. STATISTICAL ANALYSIS USED: Both parametric and nonparametric statistical tests were used. RESULTS: The EC(50) of benidipine for inhibiting contractility in the distal ureter was found to be 54.68 nM. Benidipine was found to have a greater inhibitory effect on the distal ureter than on the proximal ureter. It was also found to inhibit amplitude of spontaneous ureteric contractility more readily than the frequency of spontaneous ureteric contractility. CONCLUSIONS: These results suggest that benidipine has differential inhibitory effects on the spontaneous contractility of the isolated ureter. Benidipine could be useful in the management of clinical conditions like ureteric colic due to its inhibitory effects on the contractility of the ureter.