Using isolated rat hearts perfused on a langendorff apparatus,ischemic preconditioning (IP) was investigated with 5 min normothermic (at 37℃) or hypothermic (at 30 ℃) ischemia, followed by 10 min of reperfusion before the arrest period, as an adjunct to St. Thomas crystalloid cardioplegia during 180 min ischemia. After basline functional data were obtained, IP was induced 1 control hearts underwent no IP. Results showed that IP improved functional recovery from ischemia during 45 min reperfusion in normothermic ischemic preconditioning group (NP) comparing with normothermic control (NC),P