Is Mg2+ important for the secretory function of the pancreatic beta-cells?

The interactions between Mg2+ and Ca2+ and the total content of magnesium were studied in beta-cell-rich pancreatic islets from ob/ob mice. High concentrations of Mg2+ inhibited basal intracellular 45Ca net uptake as well as that stimulated by K+ depolarization or Na+ omission, suggesting that Ca2+ and Mg2+ can compete for both the voltage-dependent Ca2+ and the Na+ channels. The magnesium content of the islets was remarkably stable being affected only under extreme conditions. It is suggested that the physiological stimulation of insulin secretion does not depend on dynamic fluctuations of magnesium metabolism.