Venodilator effects of pranidipine, a 1,4-dihydropyridine Ca2+ channel antagonist, in rats: Comparison with nifedipine and amlodipine

The effects of pranidipine, a dihydropyridine Ca2+ channel antagonist, on mean circulatory filling pressure, an index of body venous tone, were compared with those of other dihydropyridines (nifedipine and amlodipine) and nitroglycerin in anaesthetized hexamethonium-and norepinephrine-treated rats. In this study, the compounds were used at doses having a equi-hypotensive effect. Intravenous bolus injection of pranidipine (10 and 30 mu g/kg) significantly decreased mean circulatory filling pressure in a dose-dependent manner, as did nitroglycerin (30 and 100 mu g/kg). Nifedipine (30 and 100 mu g/kg), however, did not affect mean circulatory filling pressure. Amlodipine (1000 and 3000 mu g/kg) decreased mean circulatory filling pressure only at the higher dose. These results suggest that pranidipine has a greater venodilator effect than nifedipine and amlodipine.