Activation of Mitochondrial ATP-sensitive Potassium Channels Prevents Neuronal Cell Death After Ischemia in Neonatal Rats

Activation of mitochondrial ATP-sensitive potassium channels (mK(ATP)) has been shown to protect against cell death following ischemia/reperfusion in the heart but not in brain. We examined whether mK(ATP) activation with diazoxide (DIZ) prevents neuronal cell death following hypoxia-ischemia (HI) in 7-day-old rat pups. Rat pups were subjected to HI (left carotid ligation; 8% O(2); 2.5 h), following administration of vehicle, 1.9 mg/kg DIZ, 3.8 mg/kg DIZ or DIZ plus 10 mg/kg 5-hydroxydecanoic acid (mK(ATP) antagonist). Total infarct volume was reduced from 99.8+/-2.7% in vehicle animals to 80.6+/-4.2% in 3.8 mg/kg DIZ treated animals (n=85, P<0.05). Western blotting showed K(ATP) subunits concentrated in mitochondria. Fluorescent studies indicated DIZ directly depolarized the mitochondria. In conclusion, selective opening of mK(ATP) prior to HI results in neuroprotection in immature rats.