The Separation Of The Plasma Membrane Calcium And Magnesium Atpase, Function And Mechanism Of Purification And Reconstruction Of Their Hypertension Status

Essential hypertension is a serious cardiovascular disease with high morbidity in the world. The mechanism of hypertension has been widely investigated in the biological and medical fieldsmore than ninety years . But it still remains to be elucidated. The persistent contraction of resistance blood vessels is showed to be resulted from higher calcium concentration in the vascular smooth muscle cell (VSMC), so the handling of intracellular free calcium concentration ([Ca²⁺]i) is one of the key problems in pathogenesis of hypertension.Intracellular free calcium concentration in VSMC is controlled by the following factors: Calcium influx from outside VSMC; calcium efflux from inside VSMC and the handling by subcellular organs such as sarcoplasmic reticulum. Plasma membrane Ca²⁺-Mg²⁺-ATPase ( PMCA ) is a active transporting system of calcium and plays an important role in reducing [Ca²⁺]i, but its role in the pathogenesis of hypertension is uncertain. So the question of disturbances of Ca²⁺-Mg²⁺-ATPase activities is an important and interesting one in the mechanism of hypertension. Because of this, our research is mainly designed to answer the following question. If there are functional changes of Ca²⁺-Mg²⁺-ATPase activities in hypertension; which is the key point in this subcellular organ? How and Why?The main results of the studies are as follows:1. The methods of purification and reconstitution of Ca²⁺-Mg²⁺-ATPase were set up and Ca²⁺-Mg²⁺-ATPase from both spontaneously hypertensive rat ( SHR ) and control rat ( CR ) were isolated, purified and reconstituted in the study. The results showed the purified and reconstitute Ca²⁺-Mg²⁺-ATPase has functional and normal activities. This work is not reported before .2. The functional changes of Ca²⁺-Mg²⁺-ATPase and possible mechanism of it in hypertension were studied systematically. Results revealed that under hypertension state: A. There is indeed functional changes of Ca²⁺-Mg²⁺-ATPase in hypertension. Either basic activity in the membrane state or the activity in the mimic state of Ca²⁺-Mg²⁺-ATPase in hypertension is reduced. B. The basic activity of the enzyme in membrane state can be modulated by regulating factors from both inside and outside of erythrocyte. These factors are coordinate with each other and can increase the activity of the enzyme. It suggested that there is possibly a physiological feedback mechanism in hypertension state; C. The inside regulating factors from SHR erythrocyte has stronger effect on the enzyme activities than that of outside regulating factors. This is possiblly caused by the reaction of higher [Ca²⁺]i in erythrocyte under hypertension state. D. The plasma membrane plays an important role in...