The Effects of Enalapril and Losartan on Left Ventricular \;Hypertrophy and Myocardial Fibrosis in SHR

Aim:To investigate the left ventricular hypertrophy and myocardial fibrosis in spontaneously hypertensive rats(SHRs),and the protective role of enalapril and losartan. Methods:Enalapril(20 mg·kg 1 ·d 1 ) or losartan(25 mg·kg 1 ·d 1 ) or their combination(enalapril 10 mg·kg 1 ·d 1 ,losartan 12.5 mg·kg 1 ·d 1 ) was administered from 10 to 16 weeks of age of SHRs( n= 30).Male,age matched untreated SHR and Wistar Kyoto(WKY) rats were served as controls.Systolic blood pressure(SBP), left ventricular mass and left ventricular mass index(LVMI) were determined.Left ventricular collagen contents were measured by spectrophotometric method.Cardiomyocytes size,the parameter and content of collagen on pathological tissue slices were assessed with computerized video processing. Results:Compared with WKY rats,the SBP,LVMI,left ventricular collagen contents,cardiomyocytes size,collagen volume fraction(CVF) and perivascular circumferential collagen area(PVCA) were significantly increased in SHRs( P 0.001),and substantially reduced in treated SHRs than that in untreated SHRs( P 0.01).There were no difference in these parameters between enalapril group and losartan group.Except the SBP, the combination of enalapril with losartan reduced all markers more pronouncedly than enalapril or losartan alone. Conclusion:Enalapril and losartan decrease blood pressure,reverse early left ventricular hypertrophy and myocardial fibrosis in SHR. Little difference of effects has been found between them. The combination of enalapril with losartan is more effective than monotherapy except effect on the SBP.