Objective To explore the influence of NMDA receptor specific inhibiter MK801 on the Cyt c release from mitochondria to cytosol in hippocampal CA1 of rats in cerebral ischemia/reperfusion,ischemia preconditioning and preischemia preconditioning.Methods The whole cerebral ischemia and ischemia preconditioning model were established by 4-vessel occlusion in adultmale Sprague-Dawley(SD)rats,the rats in the administration group before ischemic preconditioning for 60minuteswas given intraperitoneal injection of MK801 3mg/kg.SD ratswere randomly divided into the sham operation group,the cerebral ischemia/reperfusion group,the cerebral ischemia/reperfusion plus normal saline group,the MK801 treatment before ischemia preconditioning group,the normal saline treatment before ischemia preconditioning group and the ischemia preconditioning group.Whether themitochondria and cytosol were successfully separated in the experiment was demonstrated by detecting the distribution of themitochondrialmarker protein COXⅣ in the isolated mitochondria and corresponding cytosolic fractions.The mitochondrial components of the CA1 neurons in the hippocampus of different treatment groups and the level of Cyt c and COXⅣin the corresponding cytosolic fractions was analyzed by using immunoblotmethod.Results Mitochondria and cytosolwere separated successfully,COXⅣwas only foundin themitochondrial fractions of each group,and the COXⅣ immune activity were not detected in the cytoplasmic fractions of each group.Compared with the sham operation group,the release of Cyt c from mitochondria to cytosol in the cerebral ischemia/reperfusion group was significantly increased,with significant difference(P<0.05).Compared with cerebral ischemia/reperfusion group,the release of from mitochondria to cytosol in the ischemia preconditioning group was significantly decreased,with significant difference (P<0.05).Compared with the ischemia preconditioning group,the release of Cyt c from mitochondria to cytosol in the MK801 treatment before ischemia preconditioning group was significantly increased,with significant difference(P<0.05).Conclusion Ischemia preconditioning can obviously depress the release of Cyt c from mitochondria to cytosol induced by cerebral ischemia/reperfusion through NMDA recepter,which provides a theoretical basis for clinical treatment of cerebral ischemia/reperfusion injury.