心肌缺血日负荷对新西兰兔血管内皮生长因子表达的影响

要目的:观察心肌缺血日负荷对新西兰兔血管内皮生长因子(VEGF)表达的影响。方法:健康成年新西兰兔38只,体重2.0—2.5kg。根据日缺血次数随机分为2次/日组、4次/日组、6次/日组、假手术组以及正常组。将气囊梗阻器安装在冠状动脉左室支,制作间断性心肌缺血模型。缺血负荷为2min/h,缺血刺激4周。取缺血区心肌观察形态学变化;WesternBlotting方法检测VEGF蛋白在缺血区心肌的表达水平;取兔术前和缺血刺激前、后24h血清检测肌钙蛋白(cTnI)。结果:气囊充气可以有效、迅速地诱发心肌缺血;与假手术组和正常组相比,缺血刺激2次/日组、4次/日组、6次/日组缺血心肌VEGF表达升高(P<0.05),各缺血刺激组间的VEGF表达无差异;各组左室支支配区未见心肌坏死和血栓形成;兔缺血刺激后24h血清肌钙蛋白无明显升高。结论:持续4周的间断性心肌缺血对心肌无损伤,可以显著提高缺血区心肌VEGF表达增加,不同刺激频率对其表达无明显影响。

The effect of daily myocardial ischemic burden on expression of VEGF in heart of New Zealand rabbit

Objective:To explore the effect of daily ischemic burden on expression of vascular endothelial growth factor(VEGF) in myocardium of New Zealand rabbit.Method:According to daily ischemic frequency, 38 adult New Zealand rabbits(2.0-2.5kg) were assigned to five groups: control group, sham-operate group and study group. The study groups were designed as 2,4 and 6 times group according to the daily frequency of ischemic stimulation.Intermittent myocardial ischemia model was performed by a balloon occluder on the left ventricle coronary artery.Seven to ten days after surgery, 2-min coronary occlusions per hour was performed daily and lasted for 4 weeks through inflating balloon occluder, meanwhile ECG was observed. The ischemic myocardium was sampled for histological examination. The expression level of VEGF in ischemic myocardium was analyzed by Western Blotting. Blood serum was obtained on baseline, pre and 24h post ischemic stimulation for detecting cardiac troponin I(cTnI).Result:The inflation of balloon occluder induced elevation of ST segment immediately, indicating onset of myocardial ischemia. Compared with the control group and sham-operate group, the expression of VEGF was obviously increased in the ischemic groups(P<0.05). There was no myocardial cell degeneration and thrombus found in all subjects, and no significantly increasing in blood cTnI 24h post ischemic stimulate.Conclusion:Four weeks intermittent myocardial ischemia may increase the expression of VEGF in myocardium without irreversible myocardial damage. Increase of daily ischemic frequency does not enhance VEGF expression.