心肌缺血再灌注损伤亚细胞Ca~(2 )反常与ATP酶泵功能抑制

目的　研究心肌缺血再灌注损伤亚细胞Ca2 分布、含量及ATPase活性变化 ,探讨Ca2 反常与ATP酶泵功能抑制的关系。方法　采用离体心脏灌注模型 ,电子探针显微分析测定心肌缺血再灌注原位亚细胞Ca2 变化 ;电镜酶细胞化学及生化方法测定ATPase分布及活性变化。结果　心肌缺血 30min再灌注 30、6 0min肌浆网及肌膜Ca2 明显减少 (P <0 .0 1) ,而胞浆及线粒体内Ca2 明显增加 (P <0 .0 1)。再灌注肌浆网及肌膜Ca2 减少与胞浆及线粒体Ca2 增加呈负线性相关 ,r分别为- 0 .96 4和 - 0 .994,胞浆与线粒体Ca2 变化呈正线性相关 ,r为 0 .997。心肌缺血 30minATPase活性明显降低 ,缺血 30min再灌注 30及 6 0min进一步加重。结论　心肌缺血再灌注Ca2 超载发生在亚细胞水平 ,即亚细胞Ca2 的重新分布。ATPase泵功能抑制是心肌缺血再灌注亚细胞Ca2 紊乱的直接原因之一。

The relationship between subcellular calcium paradox and ATPase pump inhibition in myocardial ischemic and reperfusion injury

Objective To examine the location, distribution and content change of calcium ion within subcellular organelle and ATPase activity in myocardial ischemic and reperfusion injury, to evaluate the relationship between calcium paradox and ATPase pump inhibition. Methods The change of myocardial subcellular calcium ion in situ in the isolated ischemic and reperfused rat heart were determined by calcium cytochemical probe (potassium pyroantimonate, PPA) and electron probe microanalysis technique (EPMA), Similar myocardium was assayed for the change of the distribution and activity of Na K ATPase and Ca 2 ATPase using electron microscopic enzyme cytochemical as well as a biochemical procedure. Results It was found that calcium ion within sarcoplasmic reliculum (SR) and sarcolemma (SL) decreased significantly, while a large amount of calcium ion appeared in myocardial cytoplasm and mitochondria 30 and 60 min after reperfusion. ( P <0.01). The calcium ion decrease within SR and SL is negatively correlated with the calcium ion increase in cytoplasm and mitochondria during reperfusion. ( r =-0.964 and -0.994 respectively). The change of calcium content in cytoplasm and mitochondria was positively correlated, r =0.997. The activity of Na K ATPase and Ca 2 ATPase was depressed significantly during ischemia, and the situation became worse at 30 and 60 min after reperfusion. Conclusions The study directly demonstrated that the intracellular calcium overload during myocardial ischemia and reperfusion occurs in subcellular level, that is the redistribution of subcellular calcium ion. The functional depression of Na K pump and Ca 2 pump are the important link and direct reason for subcellular calcium disorder in myocardial ischemia and reperfusion.