尼可地尔预处理保存大鼠离体心脏的实验研究

Effect of Nicorandil preconditioning of rats on storage of their heart exvivo

目的探讨尼可地尔预处理大鼠对低温保存液中离体心脏的保护作用及分子机制。方法 24只SD雄性大鼠采用抽签法随机分为2组,对照组和实验组分别腹腔注射0.1 mg.kg-1.d-1无菌0.9%氯化钠注射液(normal saline,NS)和尼可地尔(nicorandil,NCR)共9 d,最后一次注射后切取心脏并放于4℃St-Thomas心肌保存液中保存,于2、4、6、8、10、12、16、20、24 h取左心室前壁心肌组织测定丙二醛(malonaldehyde,MDA)含量并观察超微结构改变,采用免疫组化和蛋白印迹法检测内源性HSP70表达。结果尼可地尔预处理组离体心肌组织MDA含量较NS组显著降低(P<0.05),其超微结构改变也显著优于对照组。对照组离体心肌各时间点内源性HSP70仅有微量表达或无表达。尼可地尔预处理组随着离体时间延长,HSP70表达量呈类抛物线性相关,并且HSP70表达6 h达高峰,24 h后显著下降。相关分析结果表明:MDA含量与HSP表达呈负相关(P<0.05)。结论尼可地尔预处理对离体心脏有保护作用,其机制可能与内源性HSP70早期持续表达有关。

Objective To explore the mechanism of protecting effect of Nicorandil on isolated heart of rats in cold preservation solution.Methods A total of 24 SD male rats were randomly divided into a control group and nicorandil group,in which the rats were injected intraperitioneally with distilled water or nicorandil 0.1 mg·kg-1·d-1 for 9 days respectively.After the last injection,every isolated heart was stored in 4 ℃ St-Thomas solution.The myocardial tissue was taken from the anterior wall of the left ventricle at 2,4,6,8,10,12,16,20 and 24 hours respectively.The contents of MDA and the changes of ultrastructure of myocardial tissue were observed.The protein expressions of HSP70 were examined by using immunohistochemical staining and Western blotting.Results The ultrastructure of myocardial tissue changed more significantly in the nicorandil group.MDA concentrations were reduced significantly in the nicorandil group compared with those of the control group（P0.05）.With the time prolonged,the expression of HSP70 increased gradually and dropped later as parabola-related curves in nicorandil group compared with the basement expression of HSP70 in control group respectively.The peak expression of HSP70 was seen at 6 hours and significantly decreased at 24 hours in nicorandil group.The correlation between MDA and HSP70 are significant（P0.05）.Conclusion Nicorandil preconditioning may have a protective effect in the isolated rat heart by the induction of the early endogenous HSP70 expression.