Effects Of Different Heat Shock Preconditioning Intensities On Cultured Neonatal Rat Cardiomyocytes Injured By Oxidative Stress

Objective To investigate the effects of different heat shock preconditioning intensities on cultured neonatal rat cardiomyocytes injured by oxidative-stress.Methods Primary culture cardiomyocytes of neonatal rats pretreated with heat shock.0.5mmol/L(final concentration)H₂O₂ was added into the culture medium to mimic oxidative stress.Cardiomyocytes were divided into five groups:control group,H₂O₂ group,mild heat shock pretreatment (42℃,15min,recover 12h)+H₂O₂ group(HSR15min+H₂O₂ group), moderate heat shock pretreatment(HSR45min)+ H₂O₂ group and severe heat shock pretreatment(HSR90min)+ H₂O₂ group.Cell viabilities were analyzed by MTT.The apoptosis rate was evaluated with flow cytometry. The contents of superoxide dismutase(SOD),malonaldehyde(MDA)in cardiomyocytes and lactate dehydrogenase(LDH)in culture solution were measured.Results Compared with normal control group,cell viabilities and the contents of SOD in the H₂O₂ group decreased significantly(p＜0.01), whereas,the apoptosis rate,the contents of LDH and MDA in the H₂O₂ group increased significantly(p＜0.01);Compared with the H₂O₂ group, cell viabilities and the contents of SOD in the HSR15min+H₂O₂ group and HSR45min+H₂O₂ group increased significantly(p＜0.01),whereas,the apoptosis rate the contents of LDH and MDA in the HSR15min+H₂O₂ group and HSR45min+H₂O₂ group decreased significantly(p＜0.01).The consequence of the HSR90min+H₂O₂ group and the H₂O₂ group were not different obviously(p＞0.05);Compared with the HSR45min+H₂O₂ group, cell viabilities and the contents of SOD in the HSR15min+H₂O₂ group and HSR90min+H₂O₂ group decreased significantly(p＜0.01),whereas, the apoptosis rate and the contents of MDA in the HSR15min+H₂O₂ group and HSR90min+H₂O₂ group increased significantly(p＜0.01),The contents of LDH increased significantly too(p＜0.05,p＜0.01).Conclusions Heat shock pretreatment can protect primary cultured rat cardiomyocytes injured by H₂O₂.Different effects would be created on cardiomyocytes by different heat shock preconditioning intensities.