氯化镉对大鼠心肌H9c2细胞DNA损伤的作用机制

目的：研究氯化镉（CdCl2）在体外对大鼠心肌细胞DNA的损伤作用，探讨CdCl2心肌毒性作用机制。方法：以0、5、10、30、50和80 μmol?L-1 CdCl2作用于大鼠心肌H9c2细胞，采用单细胞凝胶电泳法（SCGE）检测作用6、12及24 h的DNA损伤，Western blotting法检测CdCl2作用24 h对聚ADP-核糖聚合酶（PARP）的影响，免疫细胞化学法检测细胞色素C（Cyt-C）和凋亡诱导因子（AIF）蛋白表达变化的情况。结果：随CdCl2 浓度的增大和作用
时间延长，作用12、24 h后，10、30、50和80  μmol/L剂量组大鼠心肌细胞DNA损伤程度明显，组间比较差异有统计学意义（P< 0.05或P< 0.001）。作用24 h后，30、50和80  μmol?L-1剂量组可见明显PARP裂解89 000片段。Cyt-C和AIF蛋白的表达也随着CdCl2浓度的加大而显著增高，组间比较差异有统计学意义（P< 0.05或P< 0.001）。结论：CdCl2对大鼠心肌细胞的毒性作用机制可能与诱导DNA损伤，影响PARP、Cyt-C和AIF蛋白表达有关，且具有一定的剂量依赖关系。

Mechanism of DNA damage induced by cadmium chloride in rat H9c2 cells

Objective To explore the mechanisms of DNA damage in rat H9c2 cells in vitro induced by different concentrations of cadmium chloride(CdCl2).Methods SCGE method was used to detect the DNA damage in rat H9c2 cells after exposed to 0,5,10,30,50 and 80 μmol·L-1 CdCl2 for 6,12 and 24 h.Western blotting was applied to observe the poly ADP-ribose polymerase(PARP) activity after 24 h exposure.Cytochrome-C(Cyt-C) and apoptosis inducing factor(AIF) expressions were measured by immunocytochemical method.Results With the increasing of CdCl2 concentration and exposure time,the DNA damage levels and rates of rat myocytes in 10,30,50 and 80 μmol·L-1 dose groups were increased after treated for 12 and 24 h.There were significant differences between various groups(P<0.05 or P<0.001).After treatment of CdCl2 for 24 h,the significant PARP cleavage fragment of 89 000 was found in 30,50 and 80 μmol·L-1 dose groups.With the increasing of CdCl2 concentration,the Cyt-C and AIF protein expressions were significantly increased,there were significant differences between various groups(P<0.05 or P<0.001).Conclusion The toxic mechanisms induced by CdCl2 in rat H9c2 cells may be related to inducing the DNA damage and affecting the expressions of PARP,Cyt-C and AIF.There exists dose-dependent relationship.