[The Ca pump and Ca ATPase in the erythrocytes of patients with hypertension: disorders detected in cytoskeletal membranes and in solubilized Ca ATPase].

A study of Ca-ATPase and Ca-pump activity of the erythrocyte membrane's inverted vesicles with different cytoskeletal protein status demonstrated that Ca-pump activity remained unchanged, and Ca-ATPase activity was increased by 20-40%, as compared to erythrocytes from the normotensive controls, in hypertensive patients in the absence of exogenous calmodulin. These differences are assumed to be due to disorders of erythrocyte membrane structure in primary hypertension resulting in less efficient Ca-pump operation in the inverted vesicles. In all types of membranes obtained from hypertensive patients' erythrocytes in conditions of iso-osmotic hemolysis, calmodulin-induced increment of peak Ca-ATPase and Ca-pump activity was 2 or 3 times as low as that of normotensive controls. These differences remained in evidence after the solubilization of membrane proteins with triton X-100. No differences in calmodulin influence on Ca-ATPase affinity to Ca2+ could be found. The membranes obtained in iso-osmotic conditions demonstrated no calmodulin effect on Ca-ATPase activity which is attributed to partial proteolysis of the enzyme's molecule.