FIGURE 4.

Treatment with CTTN-I peptide attenuates increases in F/G-actin ratios and force development without affecting myosin phosphorylation. A, HASM cells that had been pretreated with control or CTTN-I peptide were stimulated with ACh (100 μm; 5 min) or left unstimulated. F/G-actin ratios in cells were evaluated using the assay described under “Experimental Procedures.” Data are mean values of six independent experiments. Error bars indicate S.E. (*, p < 0.05). B, contractile response of human bronchial rings to ACh was determined, after which they were pretreated with peptides (2.5 μg/ml) for 20 min. They were then stimulated with ACh. Contractile force is compared before and after the treatment with peptides (*, p < 0.05; n = 3). C, mouse tracheal segments were treated with peptides for 20 min. ACh dose response was then determined. *, significantly lower contractile force in CTTN-I peptide-treated segments than in control peptide-treated tissues at corresponding concentrations (p < 0.01; n = 14). D, myosin light chain phosphorylation in HASM cells pretreated with peptides was assessed by immunoblot analysis. Myosin phosphorylation was similar in cells pretreated with control peptide and in cells pretreated with CTTN-I peptide (p > 0.05; n = 6).