Abstract
Pathological findings in mice exposed to 20 ppm NO_2 for 18 hours were mainly shortness and/or loss of cilia in the bronchioles. These changes returned to normal appearance 7 days after NO_2 exposure. In one group in which S-carboxymethylcysteine (S-CMC) was administered orally 7 days before NO_2 exposure and 7 more days after it, changes of the bronchioles were slight and returned to an almost normal appearance 3 days after NO_2 exposure. There was a significant difference in pathological change between this group and the group without S-CMC (P<0.01). On the other hand, there was no significant difference between the group treated with S-CMC for 7 days after exposure and the group without S-CMC. These findings suggest that S-CMC may have prophylactic effects and give the ability to repair cilia injured by NO_2 exposure in the bronchioles.
