Abstract: Abstract: Objective To observe the effects of aminoguanidine(AG) on transforming growth factor -beta1(TGF-β1) induced expression of -smooth muscle actin( -SMA) of the fibroblasts in lung from pulmonary fibrosis model rats in vitro. Methods The pulmonary fibroblasts from pulmonary fibrosis model rats were isolated from explants . We selected the proper concentrations of TGF-β1 and AG by MTT. The positive cells -SMA were observed by immunocytochemical staining. The expression of -SMA was examined by flow cytometry. Results The expression of -SMA of fibroblasts in TGF-β1 group were higher than those of Sham group ( P<0.01). Compared with TGF-β1 group, the expression of -SMA in AG+TGF-β1 group were lower (P<0.05); but compared with Sham group, they were higher significantly(P<0.01).There were no significant difference between AG group and Sham group（P>0.05）.Conclusion TGF-β1 induced the expression of -SMA in pulmonary fibroblasts from rats on d14 after administration of BLMA5 and accelerated the differentiation of fibroblasts to myofibroblasts. However, AG decreased these roles of TGF-β1.

Key words: aminoguanidine, transforming growth factor -beta 1, myofibroblast, pulmonary fibrosis