Abstract: Objective To research different concentrations of nicotine promotes the apoptosis of human umbilical vein endothelial cells and its mechanism. Methods Human umbilical vein endothelial cells were cultured in vitro. According to the concentration of nicotine, grouped as 10-6, 10 -7, 10-8 mol/L, and control.After 24 h of nicotine treatment, using CCK-8 assay tests the proliferation/activity; Annexin V - FITC fluorescence staining detects the apoptotic cells. Western blot detects the expression of protein Bax, Bcl - 2 and PARP-1, to study the mechanism of apoptosis.Results Compared with control group, in 10-6,10-7mol/L groups the proliferation/activity of HUVECs decreased(P<0.05). And the number of apoptotic cells increased(P<0.01).The target proteins expression of 10-6、10-7mol/L groups were changed as follow: Bax increased(P<0.01)，Bcl-2 decreased (P<0.01) and PARP-1 increased(P<0.01). Conclusion Concentrations of nicotine could promote the apoptosis of vascular endothelial cells, which accelerates the development of atherosclerotic disease.

Key words: human umbilical vein endothelial cells, nicotine, apoptosis