ObjectivesTostudytheeffectoflatereperfusiononcaspase-3activityofischemicmyocardiuminrabbitanditssignificance.Methods24adultrabbitswererandomlypidedinto3groups:Sham(S)withoutligationofcoronaryartery,LateReperfusion(LR)withligationfor3hoursfollowingreleasefor3hoursandPersistentIschemia(PI)withpersistentligationofcoronaryarteryfor6hours.Allanimalsweresacrificed6hoursafterthebeginningoftheexperiments.BorderregionofinfarctedmyocardiumwereincisedforanalyzingtheconcentrationofSOD,MDA,GRandtheexpressionofFADD,Caspase-3andtheapoptosisindex(AI).ResultsComparedwiththeShamgroup,LRandPIgroupexhibitedmuchhigherMDA,FADD,Caspase-3,AIandmuchlowerSOD,GR(allP<0.01).ComparedwiththePIgroup,LRgroupexhibitedhigherMDA,FADD,Caspase-3,AIandlowerSOD,GR(allP<0.05).ConclusionsLatereperfusionmarkedlyenhancedtheCaspase-3activityandthenthenumberofapoptoticcardiomyocyteinborderregionofinfractedmyocardium,whichindicatedtheexistenceoflatereperfusioninjury.ThemechanismmayinvolvethehighoxidativestressstateandexpressionofFADD.