Abstract
Guinea-pigs were exposed to 3 ppm or 9 ppm of nitrogen dioxide (6 h/day, 6 days/week) for two weeks. They were sacrificed to examine the mucociliary pathology of the trachea at 24 h postexposure. Ciliary activity was reduced in the tracheal mucosa. Deterioration of ciliary activity was more prominent in the 9 ppm exposure group. The most conspicious findings observed in the tracheal mucosa were accumulation of eosinophils into the mucosa. The number of eosinophils infiltrated in the epithelial layer was not different between the two groups. However, a larger number of activated eosinophils was observed in the 9ppm group. Also in the 9 ppm group, the epithelium showed, unlike the control group and 3 ppm group, minor changes up to major changes such as vacuolization and shedding of ciliated cells.
Such pathological changes as mentioned above could contribute to the menifestation and chronicity of respiratory allergic lesions. It is therefore possible that environmental nitrogen dioxide might have an important role for a burst of respiratory allergic diseases in modern times.
