核转录因子-κB在缺氧预处理抑制心肌细胞凋亡中的作用

目的 :研究缺氧预处理 (hypoxicpreconditioning ,HPC)对于心肌细胞蛋白激酶C(PKC)和核转录因子κB (NF κB)表达的影响 ,及其在缺氧复氧诱导心肌细胞凋亡中的作用。方法 :在培养的SD乳鼠心肌细胞制作缺氧 /复氧 (H/R)模型 ,以荧光素染料Hoechst3 3 2 5 8测定心肌细胞凋亡率 ;制备心肌细胞蛋白提取物 ,以新PKCε亚型 (nPKCε)特异性抗体测定nPKCε相对蛋白含量 ;以抗NF κB抗体检测NF κB的表达 ;并以PKC抑制剂H7与心肌细胞预孵育后 ,观察H7对于HPC诱导的PKC和NF κB表达上调以及心肌细胞保护作用的影响。结果 :缺氧复氧造成心肌细胞凋亡 ,HPC可以降低心肌细胞H/R后凋亡率 ,并诱导nPKCε和NF κB表达上调 ;PKC抑制剂H7可以消除HPC诱导的PKC、NF κB表达上调和心肌细胞保护作用。结论 :HPC可以提高乳鼠心肌细胞对于H/R的耐受性 ,其机制涉及PKC介导的NF κB表达上调。

Effects of Nuclear Factor-κB on Inhibition of Cardiomyocyte Apoptosis Induced by Hypoxic Preconditioning

Objective: To investigate the relationship among relative protein content of protein kinase C(PKC) and the expression of nuclear factor-κB(NF-κB)and the effect of hypoxic preconditioning (HPC) on cardiomyocyte apoptosis induced by hypoxia-reoxygenation.Method: In the model of hypoxia/reoxygenation (H/R) of cardiomyocytes from neonatal Sprague-Dawley rats,the apoptosis rate of cardiomyocyte was detected by the DNA specific fluorochrome Hoechst 33258. Whole cell extracts were prepared for Western blot analysis to measure the expression of PKC and NF-κB. After preconditioned by H7(the inhibitor of PKC),the effect of H7 on nPKCε and NF-κB expression,and cardioprotection induced by hypoxic preconditioning was also observed.Results: HPC significantly reduced apoptosis ratio of cardiomyocytes subjected to sustained H/R,and upregulated nPKCε and NF-κB expression 24h after brief hypoxia. The effects of HPC on nPKCε,NF-κB expression,and cardioprotection are abolished by H7. Conclusion: HPC can protect cardiomyocytes subjected to H/R from apoptosis. Expression of NF-κB mediated by PKC might involve in cardioprotection induced by hypoxic preconditioning.