Objective To explore IPC(ischemic preconditioning) and PMA reduce the size of infarcts compared with control and breviscapini(Bre.). Methods and Results Anesthetized open-chest wistar rats underwent three 5- minute episodes of preconditioning ischemia in IPC group or after administration of Bre. in Bre.group; Control group had no episodes of ischemic preconditioning; PMA was injected 5 minutes before sustained occlusion; Afte- r 90 minutes of CAO and 3 hours of reperfusion

infarct size was significantly reduced in IPC rats’ compared with control group and Bre.+IPC groups

P<0.01. Conclusion The wistar rats IPC model was stable

TTC can obviously distinguish the AN(area of necrosis) from normal myocardium. The IPC、PMA protected the myocardium from sustained ischemia-reperfusion injury.Bre. blunted the protective role of IPC. PMA imitated the protective role of IPC. Their protective mechanism will be disscused in detail in next article.