EFFECTS OF m-NIFEDIPINE ON ACTIVITIES OF NA⁺,K⁺-ATPase,Ca²⁺-ATPase AND MG²⁺-ATPase IN MYOCARDIUM AND BRAIN OF ELDERLY RENOVASCULAR HYPERTENSIVE RATS

Clipping the left renal artery induced marked hypertension and hypertrophy of theleft ventricle in elderly(24-month-old) rats. m-Nifedipine(m-Nif,ig20mg·kg^-1,qd×9wk)significantly decreased the systolic blood pressure and the weight of the left ventricle in therenovascular hypertensive rats(RVHR).In RVHR,the activities of Na⁺,K⁺-ATPase and Ca²⁺-ATPase in microsomes of themyocardium and brain Were reduced significantly compared with those in sham-operated rats.m-Nifwas found to increase the activities of these enzymes of the myocardium and brain in elderly RVHR(P>0.01).m-Nif 10～1000μmol·L^-1 in vitro elevated the activities of Na⁺,K⁺-ATPase andCa²⁺-ATPase in the myocadium and brain of RHVR.On the contrary,the myocardial and cerebral Mg²⁺-ATPase activities were higher in RVHR than in sham-operated rats.m-Nif was shown todepress markedly this enzyme both in vivo and in vitro.These results indicate that m-Nif can improvethe activities on Na⁺,K⁺-ATPase and Ca²⁺-ATPase in the myocardium and brain in elderly RVHR.