Figure 3: Effect of bosentan on collagen gel contraction. Normal (A) and scleroderma (B) lung fibroblasts were cultured in the presence of 1.5mg/ml collagen in 24-well plates, followed by 24 hours incubation in serum-free medium with or without thrombin 0.5U/ml and with or without bosentan in indicated concentrations. The degree of collagen gel contraction was calculated as the difference between diameters of wells and those of contracted gels. The experiments were performed four times and mean values ± SD are presented. The *asterisk represents statistically significant differences between cells stimulated with thrombin versus cells stimulated with thrombin and bosentan.