Effect of Losartan and A779 on myocardial interstitial fibrosis in diabetic cardiomyopathy

Objective To investigate the effect of Losartan and A779 on myocardial interstitial fibrosis in diabetic cardiomyopathy(DCM).Methods Thirty-nine male Wistar rats were intraperitoneally injected with streptozocin(STZ) to induce hyperglycemia.After 12 weeks of the STZ injection,rats whose blood glucose was higher than 16.7 mmol/L and who had polydipsia,hyperphagia and polyuria were randomly divided into 3 groups: the DCM group,the Losartan group and the A779+Losartan group.The DCM group was subjected to perfusion of normal saline into the stomach once daily,the Losartan group perfusion of Losartan once daily,and the A779+Losartan group perfusion of Losartan and injection of A779 through the tail vein once daily.At the end of the experiment,LVIDs,LVIDd,E/A,LVEF and FS were determined by ultrasound.Then the collagen level was determined by Masson staining,and the mRNA expression of the angiotensin-conversion enzyme 2(ACE2) was determined by real-time RT-PCR.Results By the end of the experiment,the LVIDs,LVIDd and the collagen level of the Losartan group and the A779+Losartan group were lower than those of the DCM group(P0.01),also the E/A,FS,LVEF levels and the expression of ACE2 mRNA of the Losartan group and the A779+Losartan group were higher than those of the DCM group(P0.01).The LVIDs,LVIDd and collagen content of the A779+Losartan group were higher than those of the Losartan group(P0.05),andE/A,FS and LVEF of the A779+Losartan group were lower than those of the Losartan group(P0.05).However the expression of ACE2 mRNA had no difference between the Losartan group and the A779+Losartan group.Conclusions Losartan ameliorates the myocardial interstitial fibrosis via Ang-(1-7).