OBJECTIVETo study the action mechanism of tetramethylpyrazine (TMP) on the proliferation of vascular smooth muscle cells (VSMCs), thus providing experimental evidence for Chinese medicine to effectively prevent restenosis.

METHODSRats' thoracic aorta VSMCs in vitro cultured (cell line A7r5) were divided into five groups, i.e., the negative control group, the angiotensin II (Ang II, 10(-6) mol/L) group, the low dose TMP (20 micromol/L) plus Ang II group, the middle dose TMP (40 micromol/L) plus Ang II group, the high dose TMP (80 micromol/L) plus Ang II group. The proliferation ratio was detected by MTT. Gene and protein expressions of Wnt4, Dvl-1, beta-catenin, CyclinD1, and collagen I and III were detected with real-time fluorescent quantitative PCR and Western blot respectively.

RESULTSCompared with the negative control group, the proliferation ratio of VSMCs obviously increased in the Ang II group (P < 0.05). Compared with the Ang II group, the proliferation ratio of VSMCs obviously decreased in the middle dose TMP plus Ang II group and the high dose TMP plus Ang II group (P < 0.05). Compared with the negative control group, gene and protein expressions of Wnt4, Dvl-1, beta-catenin, CyclinD1, Col I, and Col III were obviously up-regulated in the Ang II group (P < 0.05). Compared with the Ang II group, mRNA and protein expressions of Wnt4, Dvl-1, beta-catenin, CyclinD1, Col I, and Col III were obviously down-regulated in the middle dose TMP plus Ang II group and the high dose TMP plus Ang II group (P < 0.05). The aforesaid indices were dose-dependent in the low, middle, and high dose TMP plus Ang II groups.

CONCLUSIONTMP inhibited Ang II induced proliferation and collagen secretion of VSMCs through down-regulating Wnt signal pathway.