Magnesium-dependent calcium efflux in mammalian heart muscle

Extra and intracellular magnesium is involved in the control of myocardial calcium movements. Here we report on an increase in cytosolic calcium concentration in resting ventricular myocytes due to the withdrawal of extracellular magnesium under the condition of a blocked sodium-dependent calcium elimination. Evidence for an activation of cellular calcium efflux by extracellular magnesium showed experiments in perfused hearts. It is concluded that extracellular magnesium can modulate the intracellular free calcium concentration of the myocardial cell by its influence on calcium elimination.