The effect of ROCK on fibroblast contraction. The influence of ROCK1 on the contractile potential of isolated fibroblasts was investigated using collagen contraction gels. Cells were pre-treated with different concentration of the ROCK inhibitor Y27632 or the myosin II inhibitor blebbistatin for 1 hour and contraction was monitored as the gel areas after 24 hours compared to the initial gel areas. Paired comparison of centrally derived fibroblasts (A) or distally derived fibroblasts (C) from control subjects and COPD patients with and without Y27632 after 24 hours incubation. (B) paired comparison of centrally derived fibroblasts or distally derived fibroblasts (D) from control subjects and COPD patients with and without the myosin II inhibitor:blebbistatin after 24 hours incubation. (E) Comparison of the inhibitory effects of Y27632 and blebbistatin calculated as (Y27632-untreated) / (blebbistatin-untreated) after 24 hours incubation for distally derived fibroblasts. (F) Cytotoxicity of the used antagonists shown as viability as determined by trypan blue exclusion after 24 hours exposure. Open symbols represents fibroblasts isolated from lung explants and closed symbols fibroblasts isolated from lung biopsies. * P < 0.05, ** P < 0.01, *** < 0.001.