The calcium paradox of essential hypertension.

Three disparate observations--that calcium mediates vascular smooth muscle contraction, that calcium channel blockers lower blood pressure, and that increased dietary calcium intake can also ameliorate hypertension--constitute somewhat of a paradox. The complex interrelationships between calcium metabolism and essential hypertension are discussed in this review. Recent evidence suggests possible defects in intracellular calcium transport or in calcium binding in essential hypertension. This evidence, and the paradoxical therapeutic efficacy of both calcium channel blockers and supplemental dietary calcium, can be integrated into a single theoretic construct.