Magnesium transport in hypertension

Epidemiological, clinical and experimental evidence indicates an inverse association between Mg²⁺ levels (serum and tissue) and blood pressure. Magnesium may influence blood pressure by modulating vascular tone and structure through its effects on numerous biochemical reactions that control vascular contraction/dilation, growth/apoptosis, differentiation and inflammation. Magnesium acts as a calcium channel antagonist, it stimulates production of vasodilator prostacyclins and nitric oxide and it alters vascular responses to vasoactive agonists. Mammalian cells regulate Mg²⁺ concentration through specialized influx and efflux transport systems that have only recently been characterized. Magnesium efflux occurs via Na²⁺-dependent and Na²⁺-independent pathways. Mg²⁺ influx is controlled by recently cloned transporters including Mrs2p, SLC41A1, SLC41A1, ACDP2, MagT1, TRPM6 and TRPM7. Alterations in some of these systems may contribute to hypomagnesemia and intracellular Mg²⁺ deficiency in hypertension. In particular increased Mg²⁺ efflux through altered regulation of the vascular Na⁺/Mg²⁺ exchanger and decreased Mg²⁺ influx due to defective vascular and renal TRPM6/7 expression/activity may be important. This review discusses the role of Mg²⁺ in vascular biology and implications in hypertension and focuses on the putative transport systems that control vascular magnesium homeostasis. Much research is still needed to clarify the exact mechanisms of Mg²⁺ regulation in the cardiovascular system and the implications of aberrant transcellular Mg²⁺ transport in the pathogenesis of cardiovascular disease.