Effect of losartan and cilazapril on remodeling of myocardial interstitial collagen after myocardial infarction in rats

Objectives To investigate the effect of losartan and cilazapril on deposition of collagen in infarct zone (IZ) and non-infarct zone (NIZ) in myocardial infarction rats.Methods A rat model of acute myocardial infarction was established by ligation of left coronary artery.The rats were randomised to from treatment with losartan (15 mg/kg·d -1 ),or cilazapril (5 mg/kg·d -1 ) beginning the second day after operation for 42 days or without the treatment,and sham operated rats were used as the control group.Results Compared with the sham operation group,the myocardial infarction rats showed significant decrease in arterial pressure,maximal ascending velocity (+P'max) and maximal descending velocity of the left ventricular pressure (-P'max) and significant increase in left ventricular end diastolic pressure (LVEDP), procollagen type Ⅰ carboxyl-terminal peptide (PⅠCP) and procollagen type Ⅲ amino-terminal peptide(PⅢNP) in plasma,collagen contents and collagen type Ⅰ/type Ⅲ ratio in IZ and NIZ.Compared with infarction group without the treatment,groups treated with losartan or cilazapril had higher +P'max and -P'max,lower levels of plasma PⅠCP and PⅢNP.Cilazapril decreased significantly the content of collagen in NIZ and collagen type Ⅰ/type Ⅲ ratio,decreased slightly the collagen content in IZ.Losartan did not significantly decrease the contents of collagen both in IZ and NIZ.Conclusion Early treatment with losartan or cilazapril could improve the left ventricular function.The effect of cilazapril on fibrosis in IZ and NIZ was more significant than that of losartan.