粉防已碱对大鼠心肌微粒体ATPases的作用

THE EFFECT OF TETRANDRINE ON RAT MYOCARDIAL ATPases

体外在常规反应条件下,粉防已碱(Tet)对大鼠心肌微粒体Na^+,K^+-ATPase活性无明显影响,但浓度依赖性抑制Mg^(2+)-ATPase(IC_(50)=179μmol/L).Tet 10和100μmol/L使哇巴因(Oua)抑制Na^+,K^+-ATPase的量效曲线平行右移.Tet 100μmol/L可显著提高低K^+或高Ca^(2+)浓度时的Na^+,K^+-ATPase活性,但未能明显增加低Na^+浓度时该酶的活性.动力学分析提示Tet 100μmol/L增加Na^+,K^+-ATPase对ATP的亲和力,但不改变其最大反应速度。

The effect of tetrandrine (Tet)on Na^+, K^+ -ATPase and Mg^(2+)-ATPase in rat myocardial microsomes was investigated in vitro. Under optimal condition, Tet did not influence Na^+, K^+ - ATPase activity but concentration- dependently inhibited Mg^(2+) - ATPase with an IC_(50) of 179 μmol/L. At 10 or 100 μmol/L, Tet caused the concentration- inhibition curves for ouabain a parallel shift to the fight. Tet 100 μmol/L markedly increased the activity of Na^+, K^+ -ATPase under suboptimal K^+ or excessive Ca^(2+) condition. However, it did not significantly increase the enzyme activity when the Na^+ concentration was lower. A kinetic analysis showed that Tet increased the affinity of Na^+, K^+- ATP ase to ATP, but did not change the maximal velocity of the enzyme reaction.