Significance of intracellular free calcium and magnesium and calcium-regulating hormones with sodium chloride loading in patients with essential hypertension.

Abstract

This study was designed: (1) to test the hypothesis that the pressor response to sodium chloride loading in patients with essential hypertension is associated with disorder of divalent cations (calcium and magnesium); and (2) to clarify the relationship between intracellular free calcium concentration and serum levels of calcium-regulating factors and intracellular magnesium concentration. With sodium chloride loading, mean blood pressure, urinary calcium and magnesium excretions and platelet calcium concentration were increased, and serum total and ionized calcium, magnesium concentrations and erythrocyte magnesium concentration were decreased. Change in mean blood pressure was correlated with changes in parathyroid hormone (r = 0.49, P less than 0.05), serum total and ionized calcium (r = -0.50, P less than 0.05) and erythrocyte magnesium (r = -0.56, P less than 0.05) and platelet calcium concentrations (r = 0.46, P less than 0.05). In addition, change in platelet calcium concentration was related to changes in parathyroid hormone (r = 0.44, P = 0.05), serum total and ionized calcium (r = -0.66, P less than 0.01) and erythrocyte magnesium concentration (r = -0.49, P less than 0.05). It is concluded that the pressor effect of excessive sodium chloride intake on blood pressure in patients with essential hypertension is associated with a disorder of divalent cations and that alteration of the intracellular free calcium concentration with sodium chloride loading may occur through handling of serum total and ionized calcium, parathyroid hormone and/or intracellular magnesium concentration.