心肌梗死大鼠血管生成过程中血管生成素1及其Tie2受体的表达**☆

目的：通过检测正常心肌组织及心肌梗死后血管生成素1及其受体Tie2受体 mRNA的表达水平，探讨其在心肌梗死后的血管新生过程的作用。 方法：实验于2006-04/2007-04在北京大学医学部生物化学与分子生物学基因组实验室完成。将40只雄性SD大鼠随机分为急性心肌梗死组和假手术组，急性心肌梗死组通过结扎前降支建立心肌梗死模型，假手术组只穿线不结扎。于术后3，7，14，28 d 四个时间点，每组取5只处死，取心脏左室前壁同一部位，提取总RNA，用RT-PCR的方法，以GAPDH基因为内参，进行半定量分析检测正常心脏及梗死后血管生成素1及Tie2 mRNA的表达；同时用免疫组化的方法检测各时间点梗死区域以及梗死周边区域血管数量。实验过程中动物处置符合动物伦理学标准。 结果：40只大鼠进入结果分析。血管生成素1及Tie2在正常心肌组织中均有所表达。在心肌梗死后的28 d内，血管生成素1维持在相对不变的水平，而Tie2的表达在心肌梗死后3 d略有升高，于7 d后达顶峰，14 d后恢复正常；急性心肌梗死后7 d, 梗死区及梗死周边区域的血管数量均明显增多，并不随时间的延长而改变，维持在同一水平。 结论：心肌梗死后Tie2受体的表达上调，与血管生成的时间相吻合，提示其在心肌梗死后的血管生成和稳定过程中起了一定的作用。

Expression of angiopoietin-1 and Tie2 receptor during angiogenesis in rats with myocardial infarction

AIM: To investigate the role of angiopoietin-1 (Ang1) and Tie2 receptor in angiogenesis after myocardial infarction through detecting their mRNA expression in normal and infracted myocardium. METHODS: The experiment was conducted in the laboratory of Biochemistry and Molecular Biology, Medical Department of Peking University from April 2006 to April 2007. Forty male SD rats were randomly divided into acute myocardial infarction model group and sham-operation group. The myocardial infarction model was established in the rats of model group through the ligation of left anterior descending artery, while the rats in sham operation group were braided of the left anterior descending artery without ligation. Five rats in both groups were executed at 3, 7, 14, and 28 days after model establishment. RNA was extracted from the same site of left anterior wall, and the polymerase chain reaction was used to semiquantitatively analyze the Ang1 and Tie2 receptor mRNA expression with GAPDH gene as internal control; meanwhile, the immunohistochemistry was used to detect vascular density in and around infarction area. All the treatments for animals were accorded with the animal ethical standards. RESULTS: All 40 rats were included in the final analysis. Both Ang1 and Tie2 receptor were expressed in normal myocardium. In the 28 days after myocardial infarction, Ang1 expression kept at almost the same level without changing, but Tie2 receptor expression was slightly elevated at 3 days, reached peak value at 7 days, and returned to the baseline value at 14 days. The vascular density increased both infarction and peri-infarction area at 7 days after acute myocardial infarction, and did not change with time. CONCLUSION: Tie2 receptor expression is elevated and coincided with angiogenesis after myocardial infarction. It may play a role in the development and stabilization of the blood vessel after myocardial infarction.