%0 Journal Article %A Shuli Xia %A Patricia A. Lampe %A Mohanish Deshmukh %A Aizhen Yang %A Barry S. Brown %A Steve M. Rothman %A Eugene M. Johnson, Jr %A Shan Ping Yu %T Multiple Channel Interactions Explain the Protection of Sympathetic Neurons from Apoptosis Induced by Nerve Growth Factor Deprivation %D 2002 %R 10.1523/JNEUROSCI.22-01-00114.2002 %J The Journal of Neuroscience %P 114-122 %V 22 %N 1 %X We investigated the neuroprotective properties of two M-type K+ channel blockers, linopirdine and its analog XE991, in rat sympathetic neurons deprived of nerve growth factor (NGF). Linopirdine and XE991 promoted sympathetic neuronal survival 48–72 hr after NGF withdrawal in a concentration-dependent manner. Both drugs prevented neuronal apoptosis by blocking the pathway leading to the release of cytochrome c and development of “competence-to-die” after NGF deprivation. Fura-2 Ca2+ imaging showed no significant difference in intracellular free Ca2+([Ca2+]i) in the presence or absence of NGF; linopirdine and XE991, on the other hand, caused membrane depolarization and increases in [Ca2+]i. Whole-cell recordings showed that linopirdine and XE991 selectively blocked the M current at neuroprotective concentrations, although they additionally inhibited other K+ currents at high concentrations. Membrane depolarization and [Ca2+]i increases induced by linopirdine and XE991 were blocked by the Na+ channel blocker tetrodotoxin (TTX) or by the L-type Ca2+ channel antagonist nifedipine. TTX and nifedipine also prevented the neuroprotection elicited by linopirdine or XE991.We propose that Na+ channel activation amplifies the membrane depolarization produced by M channel blockade and is essential for subsequent Ca2+ entry via the L-type Ca2+ channel. The interaction of these three classes of ion channels highlights an integrated anti-apoptosis mechanism in sympathetic neurons. %U https://www.jneurosci.org/content/jneuro/22/1/114.full.pdf