[Antihypertrophic effect of dihydropyridines calcium channel blockers is dependent on their potential of blocking N-type calcium channel].

OBJECTIVE:To compare the effects of amlodipine, benidipine and nifedipine on myocardial hypertrophy and evaluate the underlying mechanism. METHODS:Myocardial hypertrophy model was created by transverse aortic constriction (TAC) in C57 BL/6 mice, and plasma catecholamine concentrations were measured 7 days after surgery to confirm the sympathetic activation. The 3 drugs were administered in TAC mice for 7 days and cardiac hypertrophy was evaluated according to the heart-to-body weight ratio (HW/BW). Effects of those drugs on the protein synthesis stimulated by phenylephrine in cultured neonatal cardiac myocytes were also examined. RESULTS:HW/BW and plasma concentrations of catecholamine were significantly increased in TAC mice one week after surgery in comparison with to sham-operated mice. One week after TAC, the HW/BW ratio was significantly lower in the amolodipine but not nifedipine-treated group than in the TAC group. Administration of nifedipine via minipump infusion for one week did not decrease HW/BW ratio. Treatment with amlodpine or benidipine, but not nifedipine, decreased the neonatal rat myocyte protein synthesis induced by phenylephrine stimulation. CONCLUSION:Antihypertrophic effect of DHEs on myocardium is dependent on their potential of blocking N-type calcium channel, and the underlying mechanism involves the sympathetic inhibition.