Ex vivo technique for evaluating the effect of chemical vapours on mucociliary activity

An experimental protocol has been developed for the use of rat tracheal explant to evaluate the effects of inhaled chemicals on the mucociliary function. Rats were exposed for 4 h or 7 days (24 h per day) to different concentrations of toluene diisocyanate (TDI). Each rat trachea was subsequently removed rapidly and placed in a humid chamber maintained at 37 degrees C. Mucociliary function was evaluated by video measurements of the two following parameters: mucociliary beating frequency (MCBF) and number of active (A+), partially active (A +/-) and inactive areas (A-). In control tracheas; all areas were active and the MCBF showed hardly any variation around 15.3 Hz. In rats exposed to ca. 0.27 or 0.54 ppm of TDI for 4 h, tracheas showed a significant decrease in the number of active areas and a significant decrease in the MCBF. The same changes were observed in tracheas from rats exposed to approximately 0.05 and 0.10 ppm of TDI for 7 days. After a 7 days recovery period the number of active areas and the MCBF were similar in exposed and control rats except in the group exposed for 7 days to the highest concentrations; these showed only partial recovery. The results of this study showed that this ex vivo method is useful for detecting mucociliary dysfunction.