黄芪预处理对未成熟兔心肌缺血/再灌注损伤的保护作用

Effect of astragalus membranaceus pretreatment agaist myocardial ischemia/reperfusion injury in immature rabbit hearts

目的 观察黄芪预处理对未成熟兔心肌缺血/再灌注(I/R)损伤的保护作用及其机制。方法 24只幼兔(14-21 d)随机分为三组,每组8只,利用Langendorff模型灌注其离体心脏。平稳灌注30 min后,向球囊缓慢注入生理盐水,调整左室舒张压(LVDP)为10 mm Hg。对照组:继续灌注15min;黄芪组:黄芪注射液灌注15 min;5-羟葵酸液(5-HD)组:5-HD灌注5 min,黄芪注射液灌注10min。三组心脏均经历停灌30 min(保温、保湿)、缺血自动停跳及再灌注45 min复制全心缺血再灌注(I/R)模型。观察各组的血液动力学、冠脉流出液心肌酶活性及心肌能量变化、病理学和分子生物学的改变。结果黄芪组左心功能、冠脉流量恢复及再灌后心肌组织内A11P含量明显优于对照组及5-HD组,心肌酶活性明显低于对照组及5-HD组,心肌细胞线粒体超微结构分析显示黄芪组线粒体损伤轻于对照组及5-HD组,心肌诱导型一氧化氮合酶含量高于对照组及5-HD组。结论 黄芪注射液预处理对未成熟兔心肌有一定的保护作用,其机制之一是开放KATP通道。

Objective To investigate if mitochondrial KATP channels are involved in the cardioprotective effects of astragalus membranaceus in immature rabbit hearts. Methods Twenty-four New Zealand white rabbits of both sexes aged 14-21 days weighing 300-350 g were anesthetized and heparinized. The hearts were rapidly removed after thoracotomy and mounted on a Langendorff apparatus via ascending aorta and perfused with oxygenated (95% O2-5% CO2) Krebs-Hensleit buffer (KHB) solution at 60 cm H2O (perfusion pressure) and 38 ℃ . A fluid-filled latex balloon was inserted into left ventricle via left atrium for measurement of left ventricular developed pressure ( LVDP) , Global myocardial ischemia was induced by suspension of perfusion for 30 min followed by 45 min reperfusion. The animals were randomly divided into 3 groups with 8 animals in each group : group A control;group B astragalus and group C astragalus +- 5-HD (a selective inhibitor of the mitochondrial KATP channel). In group B the hearts were perfused with astragalus 40 g· L-1 for 15 min before ischemia. In group C the hearts were perfused with 5-HD 100μmol·L-1 for 5 min followed by 10 min astragalus perfusion before ischemia. In control group the hearts were perfused with only KHB before ischemia. Coronary flow (CF), HR, LVDP and ± dp/dtmax, were measured at 5, 10, 15, 30 and 45 min of reperfusion and recorded. Coronary effluent was collected at 10 min of reperfusion for determination of CK-MB, LDH and CK levels . At the end of 45 min reperfusion the isolated heart was removed for determination of myocardial ATP and iNOS levels and electron microscopic examination.Results In astragalus group (B) LVDP ± dp/dtmax and CF recovered significantly better and myocardial ATP content was significantly higher as compared with group A and C (P < 0.05 or 0.01). The myocardial levels of CK-MD, LDH and CK were significantly lower and the myocardial iNOS level was significantly higher in astragalus group than in the other two groups ( P < 0.05 or 0.01). Conclusion Astragalus can protect myocardium from ischemia-reperfusion injury by opening the mitochondrial KATP channel in isolated immature rabbit heart.