Figure 1.

TNF-α enhances the contractile response to carbachol in murine tracheal rings. Murine tracheal rings were harvested and placed in culture overnight in an equal mixture of Ham F-12 and DMEM (vol/vol, 10% fetal bovine serum) in the presence or absence of TNF-α . Cumulative concentration-response curves to carbachol were measured on the cultured tracheal rings and compared among fresh controls (□ n = 18), or in the presence of 10 ng/ml (■ n = 12) or 50 ng/ml TNF-α (● n = 12), or in the absence of TNF-α (○ n = 7) for 24 h. Isometric measurements of tracheal reactivity were calculated as changes in milligram tensions per milligram weight (mg/mg) and expressed as percentage of 10^-5 mol/l carbachol-induced tensions. Although TNF-α appeared to augment carbachol-induced force generation in cultured murine tracheal rings, it is interesting to note that carbachol-induced increases in force generation were also increased as compared with those obtained in freshly harvested tissues. Results are expressed as mean± standard error of the mean. ^*P <0.05.