One group served as control:received DHCA and vehicle. In experiment group animals received DHCA and precondi- tioning with diazoxide(5 mg/kg bolus 15 minutes prior to CPB).

• 实验组(二氮嗪组):DHCA+二氮嗪(二氮嗪5 mg/kg,CPB前15 min静脉注入);