Role of losartan on endothelin and renin-angiotensin of spontaneously hypertensive rats

Objective To investigate the effect of losartan on blood pressure, endothelin (ET) and renin-angiotensin system in plasma of spontaneously hypertensive rats (SHR). Methods 24 16-week-old male SHR and 8 age-matched male Wistar-Kyoto rats(WKY) (as controls) were used in this study. SHR were divided into three groups (each group, n = 8), respectively fed with normal saline, losartan(30mg/kg per day), cilazapril(l .25mg/kg per day)for 12 weeks. The systolic blood pressure (SBP)was determined by the tail-cuff method. ET, renin activity and angiotensin II (Ang II ) level in plasma were measured by ra-dioimmunoassay. Results Losartan and cilazapril were lowering blood pressure significantly. The concentration of ET in plasma decreased in those treated with losartan and cilazapril. Plasma renin activity significantly elevated in losartan group. The level of Ang II was significantly elevated in losartan group than cilazapril group. Conclusion Losartan has significant effect on blood pressure. Simultaneously, losartan decreased level of plasma ET, but it elevated the concentration of plasma Ang II .