不同强度热休克预处理对氧化应激所致乳鼠心肌细胞损伤的影响

Effects of different heat shock preconditioning intensities on cultured neonatal rat cardiomyocytes injured by oxidative stress

目的:探讨不同强度热休克预处理对氧化应激所致体外培养的乳鼠心肌细胞损伤的影响。方法:用热休克预处理原代培养的乳鼠心肌细胞,向心肌细胞中加入终浓度为0.5mmol/L的过氧化氢(H2O2),以模拟氧化应激造成心肌细胞损伤。将心肌细胞分为5组:对照组(Ctrl组)、H2O2损伤组(H2O2组)、低强度热休克预处理(42℃,15min,恢复12h)+H2O2组(HSR15min+H2O2组)、中等强度热休克预处理(HSR45min)+H2O2组和高强度热休克预处理(HSR90min)+H2O2组。四甲基偶氮唑盐(MTT)法观察处理后各组细胞的活力;流式细胞仪测定细胞凋亡率;检测各组培养液中乳酸脱氢酶(LDH)含量,细胞中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量。结果:与Ctrl组比较,H2O2组的细胞活力和SOD活性都明显降低(P<0.01),而细胞凋亡率、LDH和MDA含量明显增高(P<0.01);与H2O2组比较,HSR15min+H2O2组和HSR45min+H2O2组的细胞活力和SOD活性明显增高(P<0.01),而细胞凋亡率、LDH和MDA含量明显降低(P<0.01),HSR90min+H2O2组与H2O2组无明显差异(P>0.05);与HSR45min+H2O2组比较,HSR15min+H2O2组和HSR90min+H2O2组的细胞活力和SOD活性明显降低(P<0.01),而细胞凋亡率和MDA含量明显增高(P<0.01),LDH也明显增高(P<0.05或P<0.01)。结论:热休克预处理能减轻过氧化氢所致体外培养的新生大鼠心肌细胞损伤,且不同强度热休克预处理对心肌细胞的保护作用不同。

Objective：To investigate the effects of different heat shock preconditioning intensities on cultured neonatal rat cardiomyocytes injured by oxidatlve-stress. Methods：Primary culture cardiomyocytes of neonatal rats pretreated with heat shock. 0.5 mmol/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 group with 15 min heat shock at 42℃ and recovered 12 h before H2O2 treatment, moderate heat shock pretreatment group with 45 min heat shock at 42℃ before H2O2 treatment,severe heat shock pretreatment group with 90 min heat shoch before H2O2 treatment. Cell viabilities were analyzed by MTT. The apoptosis rate was evaluated with now 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 mild heat shock prereatment group and moderate heat shock pretrentment group increased significantly （P 〈 0.01）,whereas the apoptosis rate the contents of LDH and MDA in the mild heat shock pretreatment group and moderate heat shock pretreatment group decreased significantly（P 〈 0.01）. The consequence of the severe heat shock prefreatment group and the H202 group were not different obviously （P 〉 0.05）; Compared with the moderate heat shock prereatment group,cell viabilities and the contents of SOD in the mild pretreatment group and severe pretreat- ment group decreased significantly （P 〈 0.01）,whereas the apoptosis rate and the contents of MDA in the mild pretreatment group and severe pretreatment group increased significantly （P 〈 0.01）. The contents of LDH increased significantly too（P 〈 0.05,P 〈 0.01）. Conclusion：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.