Intracellular free calcium and plasma calcium in patients with essential hypertension. Is there a correlation between extracellular and intracellular disorders of calcium regulation in essential hypertension

: Alterations in intracellular free calcium regulation as well as disturbances of extracellular calcium homeostasis have been observed in patients with essential hypertension. It has been hypothesized that a generalized defect of calcium regulation might be of importance in the pathogenesis of essential hypertension. In one hypothesis a primary calcium-deficiency in essential hypertension has been linked to subsequent membrane instability and altered intracellular free calcium concentrations. We therefore investigated the relationship between intracellular free calcium concentrations in platelets and ionized as well as total plasma calcium in patients (n = 38) with essential hypertension and in age-matched normotensive subjects (n = 35). Intracellular free calcium in hypertensive patients was elevated by 13% (p less than 0.05) although there was a wide overlap between the values of the two groups. However, no difference with regard to the ionized or total plasma calcium concentrations could be observed. Total plasma calcium concentration, ionized plasma levels as well as intracellular free calcium were positively correlated (p less than 0.05) with mean arterial blood pressure. No correlation however was found between the extracellular and intracellular calcium compartments. We therefore could not observe a generalized defect of calcium regulation in essential hypertension, and extracellular calcium concentrations do not seem to be related to intracellular calcium derangement in this disease.(ABSTRACT TRUNCATED AT 250 WORDS)