Exposure of piglet coronary arterial muscle cells to low concentrations of Mg2+ found in blood of ischemic heart disease patients result in rapid elevation of cytosolic Ca2+: Relevance to sudden infant death syndrome

Exposure of cultured piglet primary neonatal coronary arterial smooth muscle cells to concentrations of ionized Mg2+ ([Mg2+](0) (i.e., 0.48, 0.3, 0.15 mM) found in blood of patients presenting with ischemic heart disease and in hypoxic neonates resulted in concentration-dependent elevation in intracellular free Ca2+ ions ([Ca2+](i); the lower the [Mg2+](0), the higher the [Ca2+](i) rise. The lowest concentration of [Mg2+], tested, i.e., 0.15 mM, resulted in a clear rounding-up (i.e., contraction) of many of the coronary smooth muscle cells; reintroduction of normal 1.2 mM [Mg2+](0) failed to restore either normal [Ca2+](i) or cell shape. (C) 1997 Elsevier Science B.V.