Aim To determine the effect of scutel laria barbata alkaloid(LCLAs)on proliferation of cultured vascular smooth muscle cell(VSMC)induced by endothelin(ET). Methods Rat aortic VSMC was cultured and divided into four groups: ET group,ET+LCLAs group,ET+BQ-123(the selective ETA receptor antagonist)group and control group,then the cell proliferation activity was subsequently quantified by cell counting kit-8 to count cell number,~3 H-TdR incorporation to measure DNA synthesis and quantitative immunohistochemical technique to investigate the expression of proliferating cell nuclear antigen(PCNA)in VSMC.Cytotoxicity was measured by Lactate Dehydrogenase(LDH)colorimetry and Trypan blue exclusion tests. Results Compared with the control group,ET-1(10~(-7)mol/ L)significantly enhanced the proliferation activity of VSMC(p<0.01),50 mg/L LCLAs inhibited the increase of cell number(6.01±0.05,p<0.05) and ~3 H-TdR incorporation(1 464±45 counts/min,p<0.05)compared with ET group,but has no evident effect on the proliferation activity of PCNA.100,200 mg/L LCLAs and 10~(-6)mol/L BQ-123 markedly decrease the cell number(5.73±0.09,4.81±0.08,4.77±0.06,respectively),~3 H-TdR incorporation(1 263±41,1 129±49,1 140±56 counts/min,respectively)and the expression of PCNA(350±29,341±53,336±39,respectively)compared with ET group(p<0.01). Conclusions LCLAs(50～200 mg/L)inhibited ET-1-induced proliferation of VSMC in a dose-dependent manner and the effect was not due to nonspecific cytotoxicity.