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 dens ity of dihydropyridines (DHP) binding sites in the cell membranes of l eft ventricle (LV) and brain in elderly renovascular hypertensive rats (RVHR) with LV hypertrophy. METHODS: Renovascular hypertension was pr oduced by clipping the left renal artery in 20-month-old rats. The aff inity 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 an d the LV weight (P < 0.01). Though not affecting the density of DHP re ceptor (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 . L V). 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 hyp ertrophy 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 hypertr ophied rats.