[Effects of m-nifedipine on activities of Na+,K(+)-ATPase, Ca(2+)-ATPase and Mg(2+)-ATPase in myocardium and brain of elderly renovascular hypertensive rats].

Clipping the left renal artery induced marked hypertension and hypertrophy of the left ventricle in elderly (24-month-old) rats. m-Nifedipine (m-Nif, ig 20 mg.kg-1, qd x 9 wk) significantly decreased the systolic blood pressure and the weight of the left ventricle in the renovascular hypertensive rats (RVHR). In RVHR, the activities of Na+, K(+)-ATPase and Ca(2+)-ATPase in microsomes of the myocardium and brain were reduced significantly compared with those in sham-operated rats. m-Nif was found to increase the activities of these enzymes of the myocardium and brain in elderly RVHR (P > 0.01). m-Nif 10-1000 mumol.L-1 in vitro elevated the activities of Na+, K(+)-ATPase and Ca(2+)-ATPase in the myocardium and brain of RHVR. On the contrary, the myocardial and cerebral Mg(2+)-ATPase activities were higher in RVHR than in sham-operated rats. m-Nif was shown to depress markedly this enzyme both in vivo and in vitro. These results indicate that m-Nif can improve the activities on Na+, K(+)-ATPase and Ca(2+)-ATPase in the myocardium and brain in elderly RVHR.