| Objective:To investigate the expression of angiopoietin2/tie2 in the rat after myocardial infarction and observe the formation of neovascularization in the infarcted peripheral region,and to explore the relationship between angiopoietin2/tie2 and angiogenesis.Methods:Eighty healthy male SD rats were randomly divided into sham-operation group(n=40)and MI group(n=40).MI model was established by occlusion of the left anterior descending artery,while the sham-operation group was braided of the left anterior descending artery without ligation.Eight rats in both groups were executed at 1,3,7,14,28 days after model establishment,meanwhile serum and myocardial tissues were retained.Enzyme-linked immunosorbent assay(ELISA)was used to detect the serum expression of Ang2/tie2,the rat cardiac function was evaluated by echocardiography,the myocardial expression of Ang2,tie2 and CD105 were analyzed by immunohistochemical technique.Results:(1)Echocardiography showed the left ventricular internal diameter at end-diastol(LVIDd)in MI group was significantly higher than those in sham operation group(P<0.01),left ventricular fractional shortening(LVFS)and left ventricular ejection fraction(LVEF)were significantly lower than those in sham operation group(P<0.01);compared with the 3d MI group,the LVEF and LVFS were increased(P<0.05),LVIDddecreased(P<0.05)in 14 d MI group.(2)In addition to the 1d MI group,the levels of serum Ang2 and tie2 in MI group were higher than those in the sham operation group(P<0.05).The expression of Ang2 in MI group increased gradually over time;compared with the 1d MI group,the expression of Ang2 increased significantly in other MI groups(P<0.01).Compared with the 3d MI group,though the expression level of Ang2 in7 d and 14 d MI groups was increased,there was no statistical significance(P>0.05),the expression of Ang2 in 28 d MI group was significantly higher(P<0.05).However,the expression of tie2 increased slightly at 3d after operation,decreased slightly at 7d,and was not significantly higher than that of 1d MI group(P>0.05),which was significantly higher in 14 d and 28 d MI group(P<0.01).(3)The results of immunohistochemistry showed that Ang2 and tie2 were expressed slightly in sham operation group.The expression of Ang2 and tie2 protein in MI group was significantly higher than that in sham operation group,and the expression of Ang2 increased over time.The expression of tie2 did not change in 1d,3d and 7d MI groups,and increased significantly in 14 d and28d MI groups.(4)The microvessel density(MVD)of MI group was significantly higher than that of sham operation group at different time points(P<0.05).The MVD increased gradually from 1d to 7d after operation in MI group,and then maintained at the same level over time.Conclusions:The expression of Ang2/tie2 was up-regulated after myocardial infarction.The expression level of Ang2/tie2 was positively correlated with the number of neovascularization after myocardial infarction,suggesting that Ang2/tie2 may promote the formation of neovascularization after myocardial infarction. |
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