高血压大鼠红细胞膜Ca^（2＋），Mg^（2＋）─ATP酶对Ca^（2＋）反应的变化及Mg^（2＋）的作用

THE CHANGES OF REACTION OF ERYTHROCYTE MEMBRANE Ca￣(2+), Mg￣(2+)-ATPase TO Ca￣(2+) AND THE EFFECT OF Mg￣(2+) ON THEM IN HYPERTENSIVE RATS

本实验观察了正常及高血压大鼠红细胞膜Ｃａ２＋，Ｍｇ２＋－ＡＴＰ酶对不同浓度Ｃａ２＋及Ｍｇ２＋的反应。结果表明：（１）在自发性高血压大鼠（ＳＨＲ），此酶最适反应的Ｃａ２＋浓度为１０－６ｍｏｌ／Ｌ；ＷＫＹ大鼠为１０－４ｍｏｌ／Ｌ；两肾一环型肾性高血压大鼠（ＲＨＲ）为１０－７ｍｏｌ／Ｌ，Ｗｉｓｔａｒ大鼠为１０－４ｍｏｌ／Ｌ，Ｃａ２＋高于以上各相应浓度时该酶活性受到抑制；（２）作为该酶激动剂的Ｍｇ２＋有其最适激活浓度，在ＷＫＹ大鼠、ＲＨＲ及Ｗｉｓｔａｒ大鼠均为４．５ｍｏｌ／Ｌ；（３）高浓度Ｍｇ２＋（３６．０ｍｏｌ／Ｌ）可以逆转高浓度Ｃａ２＋对该酶的抑制作用。以上结果表明，底物Ｃａ２＋浓度的变化对Ｃａ２＋，Ｍｇ２＋－ＡＴＰ酶的催化活性影响极大，该酶活性的促发及维持必须有适宜浓度的Ｍｇ２＋。高血压时此酶对Ｃａ２＋的敏感性增高，且Ｍｇ２＋对酶保护作用更为明显。本结果提示，胞内高浓度Ｃａ２＋不仅是高血压发生的原因之一，并可能与其发展及恶化有关。

By using inorganic phosphate measurement technique, the changes in reactions of erythrocyte membrane Ca2+, Mg2+-ATPase to different concentrations of Ca2+ were observed in hypertensive rats as well as normotensive controls. It was found that (1) the maximal ATPase activity was measured when Ca2+ concentration (in mol/L) was 10-6 in SHR, 10-4 in WKY and Wistar rats and 10-7 in RHR (two kidney-one clip), but the activity was inhibited when the Ca2+ concentration was raised above the aforementioned corresponding Ca2+ concentration for each group; (2) as an activator of Ca2+, Mg2+-ATPase and Mg2+-ATPase, Mg2+ had its optimal concentration for the maximal activation, which was found to be 4.5 mmol/L for WKY, RHR and Wistar rat; (3) high Mg2+ concentration (36.0 mmol/L) could reverse the inhibition of ATPase activity induced by high concentration of Ca2+. The results indicated that (1) the changes of Ca2+ concentration could significantly affect the catalytic activity of Ca2+, Mg2+-ATPase; (2)in order to maintain the ATPase activity, the presence of adequate amount of Mg2+ would be necessary; (3) the ATPase was hypersensitive to Ca2+ in hypertension. It is suggested that the elevated intracellular Ca2+ level is not only the important factor in pathogenesis of hypertension,but may also relate to the maintenance and aggravation of this disease.