Time-course for IL-1β effects on the 5-HT response. Tracheal segments cultured for 1 day (A), 2 days (B), 4 days (C) or 8 days (D) in the absence (control) and presence of IL-1β (10 ng/ml). Statistical analysis was performed with two-way ANOVA with Bonferroni post-test to compare the two corresponding data points at each concentration of the two curves. Each data point is derived from 6–18 experiments and represented as mean ± S.E.M. *P < 0.05, compared with control.