['Qindan-capsule (QC) is a prescription of traditional Chinese medicine for the treatment of hypertension. We investigated the effect and mechanism of QC-containing serum on proliferation of aortal adventitial fibroblasts (AFs) and composition of extracellular matrix (ECM). We also tested whether the Smad3 signaling pathway is activated in the progress.', 'AFs were cultured by tissue explant in vitro. The proliferation of AFs induced by transforming growth factor beta1 (TGF-beta1) and affected by QC-containing serum with high or low dose was detected by MTT. The protein and mRNA expressions of Smad3 and Procollagen I were observed by Western blot and Real-time PCR respectively.', 'Western blot and Real-time PCR revealed that after being activated by TGF-beta1 for 24h, the expressions of Smad3, Pho-Smad3 and Procollagen I were all higher than those in the control group. But these functions were inhibited, to some extent in different doses, by QC-containing serum. So that the proliferation of AFs which was evaluated by MTT.'] Does qindan-capsule inhibit proliferation of adventitial fibroblasts and collagen synthesis?