Potassium channel blockers attenuate hypoxia- and ischemia-induced neuronal death in vitro and in vivo.

BACKGROUND AND PURPOSE In light of recent evidence suggesting that an upregulation of K+ efflux mediated by outward delayed rectifier (I(K)) channels promotes central neuronal apoptosis, we sought to test the possibility that blockers of I(K) channels might be neuroprotective against hypoxia/ischemia-induced neuronal death. METHODS Membrane currents were recorded with the use of patch clamp recordings in cultured murine cortical neurons. Protective effects of K+ channel blockers were examined in rats subjected to transient middle cerebral artery occlusion followed by 14-day reperfusion. RESULTS The K+ channel blocker tetraethylammonium (TEA) (5 mmol/L) selectively blocked I(K) without affecting N-methyl-D-aspartate receptor-mediated current or voltage-gated Ca2+ currents. Both TEA and a lipophilic K+ channel blocker, clofilium, attenuated neuronal apoptosis induced by hypoxia in vitro and infarct volume induced by ischemia in vivo. CONCLUSIONS These data are consistent with the idea that K+ channel-mediated K+ efflux may contribute to ischemia-triggered apoptosis and suggest that preventing excessive K+ efflux through K+ channels may constitute a therapeutic approach for the treatment of stroke.