Ca ²⁺ Channel

Aranidipine (MPC-1304) is a new Ca ²⁺ channel antagonist in spontaneously hypertensive rats. Following oral administration of Aranidipine at doses of 3 and 10 mg/kg to spontaneously hypertensive rats (SHR), there are significant decreases in B _max values for specific [ ³ H](+)-PN 200-110 binding to myocardial membranes compared to the control values. The B _max values at 1 h (3 mg/kg), 1 and 6 h (10 mg/kg) are significantly decreased (47.7, 48.9 and 25.8%, respectively) compared to the control values. The effect is greatest at 1 h and decreases with time. The B _max values at 6 h (3 mg/kg) and 12 or 24 h (10 mg/kg) after the oral administration of Aranidipine are not significantly different from the control values, suggesting the disappearance of the effect of Aranidipine. The K _d values for myocardial [ ³ H](+)-PN 200-110 binding are unaltered by oral administration of Aranidipine.