Effects of menidipine on dihydropyridines binding sites in cardiac and cerebral membranes from old rats with left ventricular hypertrophy

AIM: To study the effects of menidipine (Men) on the affinity and density of dihydropyridines (DHP) binding sites in the cell membranes of left ventricle (LV) and brain in elderly renovascular hypertensive rats (RVHR) with LV hypertrophy. METHODS: Renovascular hypertension was produced by clipping the left renal artery in 20-month-old rats. The affinity and density of DHP binding sites in the cell membranes of LV and brain were assessed by radioligand assay. RESULTS: Men (20 mg . kg(-1). d(-1)ig for 9 wk) decreased markedly the systolic blood pressure and the LV weight (P < 0.01). Though not affecting the density of DHP receptor (B-max), Men markedly decreased the total number of DHP binding sites in hypertrophied LV (from 5.95 +/- 0.62 to 4.0 +/- 1.1 pmol . LV). Men also reduced B-max of DHP-binding sites in the thalamus (from 522 +/- 27 to 371 +/- 24 pmol/g protein) and hippocampus (from 498 +/- 26 to 332 +/- 32 pmol/g protein). CONCLUSION: Men reversed the LV hypertrophy from renovascular hypertension accompanied with reduced total number of DHP binding sites in the cell membranes of LV and B-max of the cell membranes of thalamus and hippocampus from elderly LV hypertrophied rats.