Altered calcium binding to erythrocyte membranes in essential hypertension: relation to magnesium

Abstract

Abnormal cellular ion transport resulting in altered membrane control over intracellular calcium may be aetiologically related to essential hypertension. Cell membrane calcium binding, which is influenced by magnesium, is an important membrane system involved in cellular calcium regulation. In this study the relationships between erythrocyte calcium binding and extra- and intracellular calcium and magnesium concentrations were determined in essential hypertensive patients (52 black, 24 white) and normotensive controls (52 black, 26 white). Calcium depletion of the erythrocytes by MgCl2 and EDTA resulted in the removal of more calcium ions from the outer erythrocyte membrane in the hypertensive group compared with the normotensive group. This may be considered as evidence of increased calcium binding to the outer cell membrane in essential hypertension. Calcium binding was greater in the hypertensive males compared with the females. In black hypertensives, serum and erythrocyte magnesium concentrations were significantly increased. In white hypertensives, serum calcium was significantly decreased and erythrocyte calcium significantly raised. Serum and erythrocyte magnesium correlated inversely with the amount of calcium released from the membranes in the black hypertensive group. The results of this study suggest that changes in magnesium levels may contribute to altered cell membrane calcium binding in essential hypertension