缺血预处理限制线粒体钙超载保护再灌注大鼠心肌

By limting mitochondrial calcium overload, ischemia preconditioning protects rat myocardium from ischemic reperfusion injury

目的研究缺血预处理(IP)对缺血大鼠心肌的保护作用。方法将Wistar大鼠随机分为对照组(CON组)、缺血预处理组(IP组)、5-羟葵酸拮抗IP组(5HD+IP组),每组8只。建立Langendorff灌注模型,平衡灌注20min,全心缺血40 min,再灌注30 min,观察比较各组血流动力学变化;再灌注末取心肌并制备线粒体,电镜观察比较形态学改变;分离、测定线粒体游离钙浓度。结果IP组与对照组相比,能明显改善缺血再灌注大鼠心脏收缩功能,左室发展压(LVDP)有显著差异(P<0.01);缺血末、再灌注末线粒体游离钙浓度显著低于对照组(P<0.01);IP组明显改善心肌、线粒体显微结构。5HD+IP组与IP组比较,再灌注各时间点大鼠心脏收缩功能指标LVDP有显著性差异(P<0.01),缺血末、再灌注末线粒体游离钙浓度显著高于IP组(P<0.01);5HD+IP组心肌细胞、线粒体形态的保存明显比IP组差。结论①IP能改善缺血再灌注大鼠心肌的收缩功能,减少线粒体钙超载,保护心肌细胞和线粒体形态和结构的完整,产生心肌保护作用;②选择性线粒体钾通道拮抗剂5-羟葵酸能翻转缺血预处理的心肌保护作用;③缺血预处理的心肌保护机制可能是通过激活线粒体ATP敏感性钾通道,限制心肌线粒体钙超载,维护线粒体整体形态和功能的完整,产生心肌保护作用。

Objective To study the cardioprotection of ischemic preconditioning. Methods Wistar rats were randomly divided into 3 groups( n = 8 each group):control group (CON) , Ischemic preconditioning group (IP)and 5 - HD (5 - hydroxyde-canoic acid) antagonized IP group(5 - HD + IP). The rat heart isolated was mounted on a Langendorff apparatus and was perfused for 20 min at 37℃ for equilibrium. Ischemic reperfusion injury was produced after 40 - min ischemia and 30 - min reper-fusion. Results The LVDP, LVEDP and mitochondrial calcium, all were less affected in IP than in CON group (P <0.01). The myocardial and mitochondrial ultrastructures were also better preserved in the IP group. When comparison was made between 5 - HD + IP group and IP group, the increase of LVEDP, the lowering of LVDP and the increase of calcium content, were more marked in the former than in the latter (P < 0.01); the preservation of myocardial ultrastructures was also poor in the former. Conclusions ①Ischenmic preconditioning can protect the rat heart from ischemia - reperfusion injury by reducing mitochondrial calcium, improving myocardial systolic function and preserving the myocardial and mitochondrial structures. ②The selective ATP sensitive potassium channel antagonist 5 - hydroxydecanoic acid can reverse the cardioprotective effects of IP.③The mechanism of the cardioprotection of IP may be to activate mitochondrial ATP sensitive potassium channel so as to limit the overload of mitochondrial calcium and to preserve the integrity of mitochondrial structure and function.