| Object: The ventricular remodeling includes not only the myocardial cell but also the cardiac interstitial collagen. Angiotension converting enzyme inhibitor (ACEI) can improve cardiac function and inhibit ventricular remodeling and myocardial fibrosis. The prostaglandin has the effect on inhibition 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 left ventricular function, myocardial fibrosis, and activity of angiotension II, prostaglandin and endothelin in a model of MI of rats.Methods: Myocardial infarction was induced in 120 Wistar male rats by ligation of the anterior descending coronary artery. Sham-operated rats served as controls (A group). One day after anterior descending coronary ligation, the operated WS rats were randomized to 4 groups, C group(Cilazapril 1mg kg-1 d-1), D group(Cilazapril 1mg kg-1 d-1 and Aspirin 50 mg kg-1 d-1), E group(Aspirin 50 mg kg-1 d-1), and B group(heart failure, the rats who did not receive any drug treatment after operation). After treated for two weeks, these rats were sacrificed. The plasma levels of angiotensionll, 6-keto-PGFl a and endothelin were measured. The myocardial collagen contents (hydroxyproline levels) including infarcted area, noninfarcted area and right ventricular were assessed in all rats. The heart and body weight, left ventricular haemodynamics were also studied.Result: There was no significantly difference in the body weight among the five group rats. Compared with Sham-operated rats, the heart weights among the four experiment groups were significantly increased. There was no significantly difference in the heart weight among the four experiment rats. The ratio of heart weight to body weight in four operated groups are significantly increased compared with Sham-operated rats. The ratios are significantly reduced in C and D group (by Cilazapril and combination of Cilazapril and Aspirin) compared with B group. There was no significantly difference in the ratio between C and D group rats. Myocardial collagen content was elevated among all four operated groups compared with Sham-operated rats. There was no significantly difference in the content of infarcted area among the four operated groups. The myocardial collagen contents in noninfarcted area and right ventricular were strikingly higher in four operated groups than sham-operated group. The content in noninfarcted area and right ventricular were reduced in C and D group compared with B group. There was no significantly difference in the myocardial collagen content between C and D group rats. It was also between B and E group. Compared with A group, there weresignificantly differences in the left ventricular haemodynamics among the four experiment groups. Furthermore, in C and D group, LVPSP, LVEDP, +dp/dtmaxand -dp/dtmax were improved compared with B group. There was no significantly difference in B and E group and C and D group. Compared with A group, the plasma hormones (Ang II, ET) in four groups were significantly increased. But they were reduced in C and D groups compared with B group. There was no significantly difference between B and E group on the plasma hormones of Ang II > ET. And it was also between C and D group. Compared with A group, the plasma hormone of 6-keto-PGFl a was decreased in four operated groups. Compared with B groups, it was improved in C and D group. But there was significantly difference between C and D group. The level was lower in D group than C group. The plasma level of 6-keto-PGFl a was more decreased in E group than B group.Conclusion: 1.There is myocardial collagen remodeling after myocardial infarction including infarcted area, noninfarcted area and right ventricular. 2.The angll and the ET play important roles on cardiac interstitial collagen in postinfarcted remodeling. 3. ACEI can improve cardiac function...
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