Abstract
Sulfur dioxide (SO2) is one of the main air pollutions. In the present study, twenty eight adult rabbits, which were devided to six experimental groups, were exposed to 20ppm of 502 for four consecutive weeks (four hours per day). 200mg/kg of carbocysteine was administered to four groups before, during, during and after, or after exposure to SO2. The ciliary activities and epithelial structure of the tracheal mucosa were examined at 24th hour in three groups and at 14th day in three groups after cessation of SO2 exposure. The ciliary activities were examined according to the direct and quantitative photo-electric method of Ohashi and Nakai. Epithelial structure was observed by scanning and transmission electron microscopy.
The following results were derived from the present observations: The tracheal mucosa obtained 24 hours after cessation of SO2 exposure revealed severely deteriorated ciliary activities and various morphological changes including decreased number of ciliated cells, and cytoplasm protuberances of epithelial cells. Recovery process of the ciliary activities and epithelial structure, if not completely, was observed 2 weeks after the exposure period. In addition, it was elucidated that administration of carbocysteine could decrease SO2 induced damages on tracheal mucociliary system as well as accelerate the recovery process of the tracheal mucosa exposed to SO2.
To sum up, it was established that SO2 affects mucociliary system of tracheal mucosa functionally as well as morphologically and that carbocysteine might have clinical benefit for some respiratory diseases.
