Dose-dependent tolerance to ozone. III. Elevation of intracellular Clara cell 10-kDa protein in central acini of rats exposed for 20 months.
Dodge-DE; Rucker-RB; Pinkerton-KE; Haselton-CJ; Plopper-CG
Toxicol Appl Pharmacol 1994 Jul; 127(1):109-123
The regional restructuring of the central acinus in rats following long term exposure to ozone (10028156) was examined, and factors, including Clara cell 10 kilodalton protein (CC10), that may make some target cell populations more resistant to injury, were identified. Fisher-344-rats were exposed to either 0.12 or 1.00 parts per million (ppm) ozone or filtered air (control group) for 6 hours/day, 5 days/week for 20 months. Changes in CC10 protein abundance in the centriacinar region were then examined. The centriacini of rat lungs in the low ozone (0.12ppm) exposure group were indistinguishable from control lung centriacini. CC10 content was also similar between the two groups. Exposure to a high level (1.00ppm) of ozone resulted in the appearance of respiratory bronchioles containing CC10 in the nonciliated epithelium and increases in the following: the number of secretory granules per cell and in amount and density of granule based CC10; proportion of CC10 per nonciliated cell; proportion of nonciliated cells in terminal bronchioles; and total amount of CC10 stored in the epithelium. The authors conclude that rats adapt to ozone exposure, at least in part, with an increase in CC10 in the central acini epithelium. This increase is caused by several factors, including increased concentration and cellular abundance of CC10 in granules and an increased mass of nonciliated secretory cells.
Laboratory-animals; Cytotoxic-effects; Cell-damage; Protein-chemistry; Protein-synthesis; Chronic-exposure; Toxic-gases; Inhalation-studies
Toxicology and Applied Pharmacology
University of California - Davis