Objective: To observe the effects of Tanyu Tongzhi(TYTZ) formula on stability of vulnerable atherosclerotic plaque of carotid artery in rats. Method: With high cholesterol lipid and 2% L-methionine feeding for four weeks

the vulnerable atherosclerotic plaque model was reproduced by operation on carotid artery endothelium for inducing sacculus pull injury. Rats were randomized into five groups: normol control group

model group

simvastatin group

vitamin complex group

TYTZ group (7.8

3.9

1.95 g·kg-1) and administrated orally for 8 weeks. At the end

the blood sample was collected to measure the concentration of Hcy

MMP-9 and TIMP-1

the protein contents of MMP-2 and TIMP-2 in plaque were detected by immunohistochemistry. Result: In contrast to model group

TYTZ (7.8

3.9 g·kg-1)

simvastatin and vitamin complex decreased the concentration of serum MMP-9 and increased the concentration of TIMP-1

the expression of MMP-9 detected in plaque was also lower. Conclusion: TYTZ formula could stablize the vulnerable atherosclerotic plaque of carotid artery through mediating MMP-9 and TIMP-1.