Dynamic changes of apoptosis and inflammation after myocardial infarction in rats

Objective To study the dynamic changes of apoptosis and inflammation after myocardial infarction(MI) in the rat infarcted hearts.Methods Sixty-eight male Wistar rats were divided into two groups of MI group(n=40) and sham group(n=28),which were subdivided into 1-,7-,14-and 28-day 4 groups.Acute MI was established by ligating the left anterior descending artery in MI group.Hemodynamics,hematoxylin-eosin staining,TTC staining,Masson staining,macrophage and apoptosis were investigated in all rats.The mRNA expression of vascular cell adhesion molecule-1(VCAM-1) and monocyte chemoattractant protein-1(MCP-1) were detected by real time PCR.Transforming growth factor-β1(TGF-β1) was examined by immunohistochemistry and Western blot.Results Cardiac function was remarkably decreaed from 1 to 14 days after MI,which was not deteriorated on the 28th day.The infarct zones were(41±3)%,(37±3)%,(38±3)% and(28±3)%,apoptosis rates were(46.3±3.0)%,(3.8±2.1)%,(3.3±2.3)% and(1.4±1.0)%,and densities were(630±72),(1360±102),(1000±98) and(223±13) piece/mm2,respectively which were all normal in sham group.Compaered wiyh those of sham group,expressions of VCAM-1 and MCP-1 were significantly increased on the 1st day after MI,decreased 14 days later,and the expression of TGF-β1 was higher at all the times after MI.Conclusion After MI,the apoptosis reaches its peak on the 1st day,and inflammatory reaction on the 7th day.Twenty-eight days is needed for a basic repair of broken heart.