Consequences of Prolonged Inhalation of Ozone on F344/N Rats: Collaborative Studies. Parts VIII and IX

Part VIII: Morphometric Analysis of Structural Alterations in Alveolar Regions Ling-Yi Chang, Barbara L Stockstill, Margaret G Ménache, Robert R Mercer, and James D Crapo

Part IX: Changes in the Tracheobronchial Epithelium, Pulmonary Acinus, and Lung Antioxidant Enzyme Activity Kent E Pinkerton, Margaret G Ménache, and Charles G Plopper

Ozone is a highly reactive gas that is a pervasive air pollutant at ground level. It is a major component of urban smog, forming when emissions from mobile and industrial sources interact with sunlight. In this report, two of studies and in the NTP/HEI Collaborative Ozone Project, were conducted to determine whether prolonged inhalation of ozone produces lasting effects on lung structure, potentially contributing to or aggravating chronic lung disease. Drs. Chang and Pinkerton and their colleagues at the Duke University Medical Center and University of California, Davis investigated the effects of this prolonged ozone exposure on respiratory tract structure. Healthy male and female F344/N rats were exposed to either 0.12, 0.5, or 1.0 ppm ozone for six hours/day, five days/week, for 20 months; control animals breathed filtered air. The investigators used light and electron microscopy to measure site-specific changes in cell and tissue characteristics. The Pinkerton group also studied the activity levels of antioxidant enzymes, which protect tissues against the potentially harmful effects of oxidants such as ozone. The investigators' goals were to characterize the nature and magnitude of the alterations in the tissue and cellular structure in the respiratory tract and the changes in enzyme activities.