wPeroxynitrite Induces Apoptosis and Decline in Intracellular Free Mg with Concomitant Elevation in [Ca2+]i in Rat Aortic Smooth Muscle Cells:Possible Roles of Extracellular and Intracellular Magnesium Ions in Peroxynitrite-Induced Cell Death

The present study demonstrates that exogenous ONOO- can result in rapid declines in intracellular free magnesium ions ([Mg2+]i) concomitant with rapid rises in intracellular free calcium ions ([Ca2+]i) and, subsequently, trigger apoptosis but not necrosis in rat aortic SMCs; high [Mg2+] significantly attenuates ONOO--induced apoptosis. ONOO-- induced apoptosis in vascular SMCs appears to involve activation of Ca2+-Mg2+-dependent endonucleases and caspase-3. Mg deficiency itself could not induce apoptosis in these SMCs, but it could significantly enhance ONOO-- induced apoptosis.