Research in the mechanism of ischemic cell death of cardiomyocyte and the role of mitochondria

在大鼠缺血再灌注模型中，观察缺血预处理、线粒体K-ATP通道开放剂、尼可地尔和二氮氧化合物对梗死面积的影响。所有这些干预措施都显著减小了梗死面积，表明线粒体K-ATP通道的开放对于减少缺血性损伤的重要性。梗死后3周采用左室压力-容积关系评价左室重构。打开线粒体K-ATP通道可减轻左室重构，重构程度与梗死面积呈正相关。尼可地尔和二氮氧化合物打开线粒体K-ATP通道的机制不同，因为尼可地尔的作用被PKC抑制剂部分抑制，而二氮氧化合物的作用不受影响。Western blotting检测PKC异构体从细胞质到线粒体的易位。这表明尼可地尔可将PKC ε和δ易位到线粒体部分，而PKC抑制剂可抑制尼可地尔的易位。此外，NO猝灭剂减少了这些同位异构体向线粒体部分的易位，这表明尼可地尔的NO供体效应激活了PKC ε和δ，随后与尼可地尔的直接打开效应协同激活了线粒体K-ATP通道。利用免疫沉淀法研究了线粒体中与PKC ε和δ结合的衔接蛋白，发现了新的衔接蛋白，这些衔接蛋白可能对线粒体K-ATP通道的激活起重要作用。

In the rat ischemia-reperfusion model, the effect of ischemic preconditioning, mitochondrial K-ATP channel openers, nicorandil and diazoxide, on the reduction of infarct size was tested. All these interventions reduced the infarct size significantly, indicating the importance of the opening of mitochondrial K-ATP cahnnels for the reduction of ischemic injury. The left ventricular remodeling was assessed by the LV pressure-volume relation at 3 weeks after infarction. The LV remodeling was attenuated by the opening of mitochondrial K-ATP channels and the extent of remodeling and infarct size was correlated. The mechanism of opening the mitochondrial K-ATP channels is distinct between nicorandil and diazoxide, since the effect of nicorandil was partially inhibited by PKC inhibitor, although the effect of diazoxide was not influenced. The PKC isoform translocation from cytosolic to mitochondrial fraction was assessed by Western blotting. This revealed that the PKC ε and δ was translocated to mitochondrial fraction by nicorandil, which is inhibited by PKC inhibitor. Furthermore, NO quencher reduced the translocation of these isoforms to the mitochondrial fraction indicates that the NO donor effect of nicorandil activates the PKC ε and δ, which subsequently activates the mitochondrial K-ATP cahnnels synergistically with the direct opening effect of nicorandil. The adaptor protein in mitochondria which bind to PKC ε and δ were explored by immunoprecipitation and new adaptor proteins are detected, which may play an important role for the activation of mitochondrial K-ATP channels.