Cell magnesium transport and homeostasis: role of intracellular compartments

Magnesium transport across the plasma membrane of cardiac and liver cells appears to be under hormonal control. The increase in cytosolic cAMP, following the adrenergic stimulation of both cell types, results in a major Mg2+ efflux from perfused rat hearts or livers and from collagenase-dispersed ventricular myocytes or hepatocytes. By contrast, the activation of protein kinase C by carbachol, vasopressin, phorbol-myristate acetate or diacylglycerol analogs induces Mg2+ accumulation in either of the experimental models. As for the role of intracellular compartments on Mg2+ homeostasis, the cAMP-mediated Mg2+ efflux largely depends on the mobilization of Mg2+ from mitochondria via the mitochondrial adenine nucleotide translocase. By contrast, Mg2+ influx appears to be related to the endo(sarco)plasmic reticulum and its dynamic handling of cytosolic Ca2+.