Objectives:To explore the effect and possible mechanisms of mild hypothermia on interferon(IFN)-α2b-induced AC16 cardiomyocytes apoptosis. Methods:Cardiomyocytes were stimulated in ordinary temperature and mild hypothermia by IFN-α2b under different concentrations for different times.Proliferation activity of cardiomyocytes was detected by CCK-8 assay.Apoptosis was detected by flow cytometry technique.The effects of different interventions on mitochondrial morphology were examined using Mito-Tracker Green and laser scanning confocal microscope,respectively.The mitochondrial membrane potentials under different intervention conditions were detected by flow cytometry.The fusion of dynamin-related protein 1(Drp1)and mitochondria,and the effects of different interventions on the mitochondria was examined by Drp1 or mitochondrial fluorescent probes and laser scanning confocal microscope.The effects of different intervention conditions on the protein expression level of Phospho-Drp1(p-Drp1)Ser616,Drp1,cleaved poly ADP-ribose polymerase1(cleaved-PARP1),poly ADP-ribose polymerase1(PARP1)were detected by Western blot. Results:CCK-8 assay and flow cytometry results showed that IFN-α2b inhibited the proliferation and enhanced the apoptosis of AC16 cardiomyocytes in a time and dose-dependent manner,these effects could be attenuated by mild hypothermia.Mito-Tracker Green,laser scanning confocal microscope and flow cytometry results showed that the extent of damage of mitochondria with different interventions were attenuated in the setting of mild hypothermia as compared with ordinary temperature.The morphology of mitochondria remained intact and the mitochondrial membrane potentials were the highest in mild hypothermia group.Injured AC16 cardiomyocytes released Drp1 from cytoplasm to mitochondria and increased mitochondrial fission,these effects were abolished after mild hypothermia.p-Drp1 Ser616/Drp1 ratio and cleaved-PARP1/PARP1 ratio were decreased after mild hypothermia,and above effects could be reversed by mitochondrial division inhibitor-1(Mdivi-1)pretreatment. Conclusions:Mild hypothermia inhibits IFN-α2b-induced AC16 cardiomyocytes apoptosis via improving mitochondrial function.