黄芪预处理对缺血再灌注大鼠心肌超微结构的保护作用

Protective function of astragalus pretreatment on the myocardial ultrastructure in rats with ischemia reperfusion

目的:探讨黄芪预处理对缺血再灌注大鼠心肌超微结构和细胞凋亡的影响及其作用。方法:实验于2004-02/10在承德医学院电镜室完成,雄性Wistar大鼠30只,随机分为黄芪预处理组(黄芪组)、缺血再灌注组和假手术对照组(对照组),每组10只。于术前1周黄芪预处理组给黄芪注射液,其他2组给生理盐水。制备缺血再灌注模型,黄芪组和缺血再灌注组大鼠结扎冠状动脉前支,40min后松开扎线,再灌注1h。对照组大鼠只穿线不结扎。术后即取光、电镜标本,电镜观察各组大鼠超微结构变化,用原位末端标记法测定凋亡细胞指数(每只大鼠观察4张切法,每张切片计数5个视野中的凋亡阳性细胞核数/总细胞核的比值,取其平均值)。结果:①心肌细胞超微病理改变:黄芪组心肌细胞轻微水肿,核不规则,肌原纤维较少,线粒体略肿胀,嵴呈波浪形,肌浆网略扩张。缺血再灌注组心肌细胞亚微结构损伤程度较黄芪组明显加重,心肌细胞肿胀明显,肌膜断裂、缺损,部分线粒体弥漫性肿胀,空泡化。对照组超微结构变化轻微,肌膜完整,肌原纤维平行排列,部分线粒体有轻到中度肿胀。②微血管内皮超微病理改变:黄芪组血管内皮细胞轻度肿胀,膜完整,核基本正常。缺血再灌注组血管内皮细胞明显肿胀,膜尚完整,心肌梗死灶内的小动、静脉和毛细血管内皮细胞发生变性、断裂和分离。对照组与黄芪组结构相似。③心肌细胞凋亡指数观察结果:黄芪组显著低于缺血再灌注组犤(14.06±9.97)%,(19.34±12.30)%,(t=1.96,P<0.05)犦,显著高于对照组犤(0.96±0.43)%,(t=4.99,P<0.01)犦,缺血再灌注组明显高于对照组(t=4.59,P<0.01)。结论:黄芪预处理对缺血再灌注的心肌细胞和内皮细胞具有保护作用,可能是通过黄芪稳定心肌细胞膜和线粒体结构和功能来实现的。

AIM： To explore the effect and its function of astragalus pretreatment on the myocardial uhrastructures and cell apoptosis in rats with ischemia reperfusion. METHODS： The experiment was done in Laboratory of Electron Microscope of Chengde Medical College from February to October in 2004. The thirty male Wistar rats were divided randomly into astragalus pretreatment group （astragalus group）, ischemia reperfusion group and sham operation control group （control group） with 10 rats in each group. Rats of astragalus group were perfused with astragalus parenteral solution one week before operation, others were given saline. The isehemia reperfusion models were prepared and the anterior of coronary artery was ligated in rats in astragalus group and ischemia reperfusion group, and 40 minutes later the line was loosen and reperfusion for 1 hour. The rats in control group only pull on thread without deligation. The light and electrtron microscope were gained after operation. The ultrastructural alterations of rats in every group were observed with electrtron microscope. The index of cell apeptosis was detected with in situ end-labeling technique. Four sections in every rat were observed, every section counted the value of nucleus quantity of apoptosis positive cells/total number of nucleus in 5 sights, and its average was gained. RESULTS： ① The pathological uhrastructure alteration of cardiac muscle cells： The cardiac muscle cells had slight edema with irregular nucleus, little myofibril, swelling mitochondrion, wave-like crista and slighdy expanded sarcoplasmic reticulum. The degree of injuring on subultrastructures of myocardial cell in ischemia reperfusion group was more serious significantly than that in astragalus group. The swelling of cardiac muscle cells was obvious with broken and defective sarcolemma. Part of mitochondrion was diffused swelling and vacuoles. The ultrastructural alteration in control group was slight with complete sarcolem-ma and parallel myofibril arrangement. Part of mitochondrion was light and medium swelling. ② The pathological ultrastructure alteration of endothelium in microvessel： The endothelial cell in blood vessel in astragalus group had light swelling with complete membrane and basic normal nucleus. The endothelial cell in blood vessel in ischemia reperfusion group had significant swelling with complete membrane. The degeneration, breakage and detachment occurred in endothelial cells in artery, vein and blood capillary in focus of myocardial infarction. The structure in control group and astragalus group was similar. ③ The observation result of apeptosis index of cardiac muscle cells： It was significantly lower in astragalus group than that in ischemia reperfusion group [（14.06%±9.97）%, （19.34%±12.30）%, （t=1.96, P 〈 0.05）], and significandy higher than that in control group [（0.96%±0.43）%, （t=4.99, P 〈 0.01 ）]. It was significantly higher in ischemia reperfusion group than that in control group （t=4.59, P 〈 0.01 ）. CONCLUSION： The astragalus pretreatment has protective effect on cardiac muscle cells and endothelial cells in ischemia reperfusion, and may obtained by stabilizing the structure and function of cell membrane and the mitochondria.