Prevention of myocardial fibrosis by using losartan to the spontaneously hypertensive rats

Objective To determine the effects of losartan on blood pressure,left ventricular hypertrophy and myocardial fibrosis of left ventricules of spontaneously hypertensive rats(SHR). Methods Antihypertensive treatment with angiotensin II receptor antagonist losartan(30mg·kg -1 ·d -1 ) was given to 16 week old male SHRs(n=8) for 12 weeks with age matched SHRs and Wistar-Kyoto rats(WKY)(n=8) received no treatment as controls.Systolic blood pressure was measured by tail-cuff method.Left ventricular weight index(LVWI) was defined according to the ratio of left ventricular weights(mg) to body weights(g).Collagen concentration was determined by measuring hydroxyprolin content.Myocardial fibrosis was evaluated by collagen concentration Type I and Type III myocardial collagens were determined by non-interrupted sodium dodium dodecyl polyacrylamide gel electrophoresis(SDS-PAGE). Results Losartan significantly reduced systolic blood pressure in SHRs(P0.05) although the value remained significantly higher than that of WKY controls.LVWI was significantly decreased in losartan treated compared with untreated SHRs(P0.05).Collagen concentration of left ventricle was lower in the losartan treated group compared with the untreated groups.The collagen types I/III ratio was greatly decreased in losartan treated group compared with untreated SHR groups,but higher than that of WKY controls. Conclusions Losartan could lower blood pressure and decreasd collagen concentration as well as left ventricular mass in SHRs.So losartan might have the potential to improve the myocardial pathology in essential hypertension.