Abstract: To explore the effects of Losartan on the expression of matrix metalloproteinases-3(MMP-3) and the number of macrophages in rabbits with atherosclerotic plaque(AP) and to explore the mechanisms of increasing the stability of AP. MethodsThe experimental atherosclerotic models were induced by endothelial injures on the ventroaorta with a balloon and hyperlipid feeding for four months. Sixteen male New Zealand rabbits were randomly divided into two groups: the model group which was fed with standard diets containing 1％ cholesterol and the Losartan group which was fed with standard diets containing 1％ cholesterol and losartan 25mg／(kg·d). The proteinum expression of MMP-3 and the positive area of macrophage cells in the AP were determined by the immunohistochemistry technique. The structures of the AP of the two groups were observerd with an electron microscope. Realtime RTPCR was used to determine the mRNA expression of MMP-3. ResultsCompared with the model group, the proteinum expression of MMP3 and the number of macrophage cells in the Losartan group were significantly decreased(P＜0.05). The expression of MMP-3 mRNA was more significantly decreased in the Losartan group than that in the model group(P＜0.05). ConclusionLosartan may stabilize vulnerable plaque by suppressing the expression of MMP-3 and reducing the number of macrophage cells.

Key words: Losartan, Atherosclerosis, Matrix metalloproteinases-3, Macrophage