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.