Abstract: AIM: Through comparing 4 ACEIs'influence in cardiac index, expression levels of typeⅠ, type III collagen, TGF-β₁, MMP-1 and TIMP-1 of diabetic rats to investigate the class effect of the ACEIs in improving myocardial interstitial remodeling of diabetic rat.METHODS: 50 male SD rats were injected streptozotocin(STZ) to induce into diabetic mellitus(DM), then the rats were divided into model group(n=9), captopril treated group (50 mg/kg, n=9), imidapril treated group(10 mg/kg, n=9), benazepril treated group(10 mg/kg, n=9) and fosinopril treated group (5 mg/kg, n=10).10 male SD rats were choosed as normal control group.Immunohistochemistry was used to measure the expression levels of type Ⅰ, type Ⅲ collagen, transforming growth factor beta 1(TGF-β₁ ) protein, matrix metalloproteinases (MMP)-1 and tissue inhibitors of metalloproteinases (TIMP)-1 protein.The mRNA of MMP-1 and TIMP-1 mRNA were measured by RT-PCR.RESULTS: By the end of the experiment, the cardiac index and the ventricle index were significantly higher in the model group than those in the normal control group (P<0.05).The expression of type I, type III collagen, TGF-β1 protein, TIMP-1 protein and mRNA were also significantly higher than in the normal control group while the expression of MMP-1 protein and mRNA were significantly lower. All the index was greatly improved in the treated groups compared with the model group. There were some difference exist in captopril among other three groups.CONCLUSION: Through increasing the expression of TGF-β₁ and TIMP-1, at the same time decreasing the expression of MMP-1, all the ACEIs could improve the myocardial interstitial remodeling, and the result was effected by the contribution to Ang Ⅱ.

Key words: myocardial interstitial remodeling, class effect, angiotensin-converting enzyme inhibitor