Fig. 2.

Cd induces α-SMA expression and increases extracellular matrix (ECM) protein accumulation as well as collagen secretion. A: primary human fibroblasts were incubated with or without CdCl₂ at different concentrations for 3 h and then allowed to recover for 24, 48, or 72 h. Cell viability was measured by thiazolyl blue tetrazolium bromide (MTT) assay, and percentage of viability relative to control was shown. Results are expressed as mean of triplicate samples and are representative of those from 3 independent experiments. B: cells were incubated with or without CdCl₂ (10 or 20 μM) for 3 h and then allowed to recover for the indicated periods of time. Immunoblotting were performed using antibodies shown above. C: cells were treated with CdCl₂ at different concentrations (top) or 20 μM at different time points (bottom), and supernatants were collected, concentrated by ultrafiltration and analyzed by Western blotting. D: cells were treated as above and the soluble collagen levels (n = 5) were evaluated by Sircol collagen assay. Horizontal bars indicate the mean values. Cells were also treated with TGF-β (2 ng/ml) for 48 h as a positive control. **P < 0.01 vs. control.