Consequences of Prolonged Inhalation of Ozone on F344/N Rats: CollaborativeStudies. Part 7. Effects on the Nasal Mucociliary Apparatus

摘要

The nose is a principal target for ozone toxicity. This study examined theeffects of chronic ozone exposure on the structure and function of the nasal mucociliary apparatus of the rat. Rats were exposed to ozone concentrations of 0.0 (control animals), 0.12, 0.5, or 1.0 parts per million (ppm), six hours per day, five days per week, for 20 months. All rats were killed seven or eight days after the end of the exposure. Immediately after death, mucous flow rates throughout the nasal passages were determined using in vitro video motion analysis. The nasal tissues were processed to detect intraepithelial mucus. Image analysis was used to quantify the amount of mucus within the nasal transitional epithelium. In rats exposed to 0.5 or 1.0 ppm ozone, mucous flow rates were markedly slower over the lateral wall and turbinates of the proximal third of the nasal airways than they were in rats exposed to 0.0 or 0.12 ppm ozone. These intranasal regions in the rats exposed to 0.5 or 1.0 ppm ozone contained marked mucous cell metaplasia and 25 to 300 times more mucus in nasal transitional epithelium than was found in control rats. There were no significant morphologic alterations or decreases in mucous flow rates in rats exposed to 0.12 ppm ozone and in control rats. The results of this study indicate that rats chronically exposed to 0.5 or 1.0 ppm ozone have significant alterations in the function and structure of the nasal mucociliary apparatus.