The Study Of Change In Ultrastruture And Histology On Myocardial Interstial Collegen Remodeling After Myocardial Infarction In Rats

Object: Left ventricular remodeling after myocardial infarction (MI) involves the hypertrophic growth of cardiomyocytes and the accumulation of fibrillar collagen in the interstitial space. Angiotension converting enzyme inhibitor (ACEI) can improve cardiac function and inhibit ventricular remodeling and myocardial fibrosis. The prostaglandin has the effect on inhibiting the cardiac interstitial collagen, which is one of the functions of ACEI. Aspirin can inhibit the activity of cyclooxygenase, and reduce the prostaglandin that is good to heart. The study is to compare the effects of ACEI alone, Aspirin alone, and combination of ACEI and Aspirin on myocardial fibrosis,collegen volume and the ratio of collegen I /III in a model of MI of rats. We also evaluate the role of the two drugs on ultrastructure of cardiomyocytes in left ventricular remodeling.Methods: The model of myocardial infarction was induced in 50 Wistar male rats by ligation of the anterior descending coronary artery. Sham-operated rats served as controls (A group). After anterior descending coronary ligated, the operated WS rats were randomized into 4 groups as follows: C group(Cilazapril 1mg.kg-1.d-1), D group(Aspirin 50 mg .kg-1.d-1), E group(Cilazapril 1mg .kg-1.d-1 and Aspirin 50 mg .kg-1. d-1), and B group(Which no receiveing any drug treatment after operation). After having treated for two weeks, these rats were sacrificed. The myocardial collagen contents (measured by collegen volume fraction CVF) including both infarcted and noninfarcted area were assessed in all rats. The ratio of collegen I /III was measured in each rat.The heart weigt and the body weight were also studied.we also discussed the feature of left ventricular remodeling with light microscope and electron microscope.Result: There was no significantly difference in the body weight among the five group rats. Compared with Sham-operated rats, the heart weights among thefour experiment groups were significantly increased. The ratio of heart weight to body weight in four operated groups is significantly increased compared with Sham-operated rats. The ratios are significantly reduced in C andE group (by Cilazapril and combination of Cilazapril and Aspirin) compared with B group. There was no significantly difference in the ratio between C and E group. Myocardial collagen content was elevated among all four operated groups compared with Sham-operated rats. The contents of infarcted area in the four operated groups were significantly higher than A group,(p<0.01),Which there was no significant difference among the four operated groups. The myocardial collagen contents in noninfarcted area were strikingly higher in four operated groups than that of sham-operated group. The contents of noninfarcted area were reduced in C and E group compared with B group. There was no significantly difference in the myocardial collagen content between C and E group rats. It was same between B and D group. Compared with A group, the ratios of collegen I /III in infracted area among the four operated groups were higher than that of A group, (p<0.01).But there were no significant difference among the four operated groups. Furthermore, the ratio of collegen I /III in noninfarcted area among the four operated groups were higher than that of A group. The ratios of collegen I /III in C and E groups were reduced compared with B and D group. But there was no significant difference between C and E group,and it was same between B and D group.Conclusion: 1 .There is myocardial collagen remodeling after myocardial infarction including infarcted and noninfarcted area. 2. ACEI has beneficial effect on interstitial collagen remodeling,which inhibit myocardial fibrosis on noninfarcted,and reduced the ratio of collegen I /III. 3. Aspirin has no effect on the interstitial collagen remodeling. 4. Combination of Cilazapril and Aspirin, the effectof ACEI on myocardial fibrosis cannot be affected .5. Cilazapril and Aspirin can improve the ultrastruture of cardiomyocytes and the interstitium after myocardial infarctio...