NO供体硝普钠损伤心肌细胞DNA的实验研究

Experimental study of the damages of NO donor on DNA of cultured neonatal rat cardiomyocytes

目的 观察外源性的 NO供体硝普钠对培养心肌细胞 DNA的损伤情况以及超氧化物歧化酶 ( SOD)和过氧化氢酶 ( CAT)的保护作用。方法 采用离体培养乳鼠心肌细胞和单细胞凝胶电泳技术 ,根据硝普钠浓度的不同和加入的自由基清除剂 SOD、CAT的不同进行分组实验。结果 外源性的 NO供体硝普钠与离体培养的乳鼠心肌细胞共培养 5小时后 ,单细胞凝胶电泳检测有典型的彗星样改变 ,并随剂量的增加其 DNA迁移度和细胞迁移率也随之增加 ,与对照组相差显著 ( P<0 .0 1) ;加入 SOD或 CAT均能明显减轻这种彗星样改变 ,二者合用效果最为显著 ( P<0 .0 1)。结论 高浓度的硝普钠严重损伤心肌细胞 DNA,自由基清除剂对此有保护作用。这在一定程度上说明 ,高浓度的 NO能导致心肌细胞 DNA单链的明显损伤 ,这可能是在某些病理条件下造成心肌细胞损伤或死亡的重要机制。

Objective To observe the damages of NO donor sodium nitroprusside (SNP) on DNA of cultured neonatal rat cardiomyocytes and the protective effects of superoxide dismutase (SOD) and catalase (CAT) in vitro Methods Cultured neonatal rat myocytes were randomly assigned to two big groups One was divided into four groups,including the control group (without SNP) and other groups with different concentrations of SNP at 10mmol·L -1 ,20mmol·L -1 and 40mmol·L -1 ;the other included four groups,group I :only 40mmol·L -1 SNP, 50 U/ml of SOD , CAT or SOD+CAT with SNP (40mmol·L -1 ) were in group Ⅱ,Ⅲ or Ⅳ respectively The damages of DNA was detected with single cell gel electrophoresis (SCGE) in individual cardiomyocyte.Results After five hours culture with SNP,the typical comet like changes of the nuclus of the neonatal rat cardiomyocytes were observed by SCGE With the increasing concentrations of SNP,both the distances of DNA migration and the rates of comet like cell increased,there were significant differences between SNP 10mmol·L -1 or SNP 20mmol·L -1 or SNP 40mmol·L -1 goup and the control (P<0 01),which were lessened by administration with SOD or CAT and more significantly by administration with SOD+CAT (P<0 01) Conclusion Large does of SNP can damage DNA of the cardiomyocytes,radical scavenger such as SOD and CAT can protect the DNA of cardiomyocytes from the damages of SNP To a certain extent,it suggests that overdoes of NO can damage the DNA strands of cardiomyocytes,which may be an important mechanism of myocardial cell damage or death under some pathological conditions