11,12.环氧二十碳三烯酸预处理与后处理对缺血/再灌注大鼠心肌的保护作用

采用Langendorff离体灌流装置,通过停灌40 min/复灌30 min复制大鼠心肌缺血/再灌注(ischemia/reperfusion,IR)损伤模型,观察11,12-环氧二十碳三烯酸(11,12-epoxyeicosatrienoic acid,11,12-EET)预处理和后处理对心肌线粒体功能以及心功能的影响,探讨11,12-EET顸处理和后处理对IR大鼠心肌的作用及其机制.将30只Sprague-Dawley大鼠随机分为对照组、IR组、EET预处理组(Pre-EET)、EET后处理组(Post-EET),每组6只.除对照组外,其它各组全心缺血40 min,再灌注30 min.监测左心室内压差(ALVP)和左心室内压升降的最大变化率(±dp/dtmax)等心功能指标,测定灌流液中乳酸脱氢酶(1actate dehydrogenase,LDH)的活性.灌流结束后,测定心肌线粒体琥珀酸脱氢酶(succinate dehydrogenase,SDH)、Ca"ATPase、Na - K -ATPase活性以及心肌超氧化物歧化酶(superoxide dismutase,SOD)活性、丙二醛(malondialdehyde,MDA)含量.结果显示:(1)与IR组相比,Pre-EET组及Post.EET组Na -K -ATPase和SDH活性均增强,Ca2 -ATPase活性均减弱,有显著性差异(P<0.05);而Pre-EET与Post-EET组间没有显著性差异.(2)与IR组相比,Pre-EET组及Post-EET组心功能明显改善,LDH漏出显著减少,心肌SOD活性明显增强,MDA含量明显降低,有显著性差异(P<0.05);而Pre-EET与Post-EET组间没有显著性差异.结果表明,11,12-EET预处理及后处理均可通过上调心肌线粒体Na -K -ATPase、SDH活性以及下调Ca2 -ATPase活性改善线粒体功能和心肌能量代谢,拮抗心肌IR损伤;11,12-EET预处理及后处理还可通过提高心肌SOD活性、降低MDA含量改善IR心肌的氧化应激.

Protective effects of 11,12-epoxyeicosatrienoic acid preconditioning and postconditioning on myocardial ischemia/reperfusion injury in rats

To explore the effects of 11,12-epoxyeicosatrienoic acid (11,12-EET) preconditioning and postconditioning on myocardial ischemia/reperfusion (IR) injury in rats, the IR injury model was built by stopping perfusion for 40 min followed by reperfusion for 30 min, and the changes of mitochondrial functions, myocardial metabolism and function were measured. Langendorff-perfused isolated rat hearts were divided into 4 groups: control group, persistently perfused with Krebs-Henseleit (K-H) fluid for 100 min; IR group, stopped perfusion for 40 min followed by reperfusion for 30 min; Pre-EET group, preconditioned with 6.24 x 10(-9 ) mol/L 11,12-EET for 5 min twice before subjected to ischemia; Post-EET group, postconditioned with 6.24 x 10(-9 ) mol/L 11,12-EET for 30 s twice before reperfusion. The computer-based electrophysiological recording system was used to measure the changes of maximal rate of the pressure increase in contract phase (+dp/dt(max)), maximal rate of the pressure decrease in diastole phase of heart (-dp/dt(max)), left ventricular end-diastolic pressure (LVEDP) and difference of left ventricular pressure (DLVP). The activities of lactate dehydrogenase (LDH) in effluent, Ca(2+)-ATPase, Na(+)-K(+)-ATPase and succinate dehydrogenase (SDH) in mitochondria were measured with colorimetry method; superoxide dismutase (SOD) activity was measured with hydroxylamine method and malondialdehyde (MDA) content in myocardial tissues was measured with TBA method. The results showed that: (1) Compared with that in the control group, the myocardial functions, the values of SOD, SDH and Na(+)-K(+)-ATPase were decreased in IR group (P<0.05); the values of LDH, MDA and Ca(2+)-ATPase were increased (P<0.05) in IR group. (2) Compared with that in IR group, the values of SDH and Na(+)-K(+)-ATPase were increased (P<0.05) and the value of Ca(2+)-ATPase was decreased (P<0.05) in both Pre-EET and Post-EET groups. But no significant differences were detected between Pre-EET and Post-EET groups. (3) Compared with IR treatment, both 11,12-EET preconditioning and postconditioning caused significant decreases in MDA content and leakage of LDH, amendment of heart functions and increases in SOD activity (P<0.05). But there were no significant differences between 11,12-EET preconditioning and postconditioning. These results indicate that 11,12-EET preconditioning and postconditioning can protect myocardium from IR injury by improving mitochondrial functions, up-regulating the activities of Na(+)-K(+)-ATPase and SDH, and down-regulating the activity of Ca(2+)-ATPase in mitochondria. Moreover, 11,12-EET preconditioning and postconditioning also elevate the activity of SOD and reduce the content of MDA, suggesting that 11,12-EET can depress the oxidative stress in IR rat heart.