Peroxynitrite 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 ([Mg(2+)](i)) concomitant with rapid rises in intracellular free calcium ions ([Ca(2+)](i)) and, subsequently, trigger apoptosis but not necrosis in rat aortic SMCs; high [Mg(2+)] significantly attenuates ONOO(-)-induced apoptosis. ONOO(-)-induced apoptosis in vascular SMCs appears to involve activation of Ca(2+)-Mg(2+)-dependent endonucleases and caspase-3. Mg deficiency itself could not induce apoptosis in these SMCs, but it could significantly enhance ONOO(-)-induced apoptosis.