Effects of m-nifedipine on dihydropyridine binding sites in cardiac and cerebral cortex cell membranes from left ventricular hypertrophied rats

m-Nifedipine (m-Nif 20 mg.kg-1.d-1 ig for 9 wk) decreased left ventricular weight in the renovascular hypertensive rats (P < 0.01). Though not significantly affecting the density of dihydropyridines (DHP) receptor (Bmax), m-Nif administered whether for prevention (6 wk postclipping) or for regression (9 wk postclipping), markedly decreased the total number of DHP binding sites in hypertrophied left ventricle (LV). m-Nif also reduced the dissociation constant (Kd) of DHP binding sites in the membranes of LV and cerebral cortex from cardiac hypertrophied rats (P < 0.01). These effects of m-Nif were similar to those of nifedipine (Nif) in the same dosage. The results suggest that m-Nif can prevent and regress the LV hypertrophy resulted from renovascular hypertension and reduce the total number of DHP binding sites in the membranes of LV from cardiac hypertrophied rats.