SITE-SPECIFIC AND CELL-SPECIFIC ALTERATION OF LUNG COPPER ZINC AND MANGANESE SUPEROXIDE DISMUTASES BY CHRONIC OZONE EXPOSURE/

The antioxidant enzymes copper/zinc (Cu-Zn) and manganese (Mn) superox ide dismutase (SOD) have been implicated in protection of the lungs fr om oxidant damage. Mn SOD in particular may be related to acquired tol erance in cells following chronic ozone exposure, In order to study th ese protective and adaptive phenomena in oxidant it?jury, the cellular location and relative abundance of Mn SOD and Cu-Zn SOD were examined in the lungs of Fischer 344 rats following exposure to 0.0 and 1.0 pp m ozone for up to 3 mo using immunolabeling and morphometric technique s. Cu-Zn SOD labeling was found to be markedly reduced following ozone exposure in epithelial cells within airways and parenchyma. In contra st, a significant increase was noted in Mn SOD labeling in the centria cinar regions of exposed lungs for both alveolar macrophages and epith elial type II cells, Mn SOD labeling per epithelial type TI cell was s ignificantly increased in alveoli 0-400 mu m beyond the bronchiole-alv eolar duet junction (BADJ), while type II cell Mn SOD labeling was sim ilar to control values with greater distance down the alveolar duct. N o induction of Mrl SOD was noted in type I epithelial cells, fibroblas ts, or Clara cells. Thus, alterations in Cu Zn and Mn SOD are both sit e and cell specific in the lungs. The differential increase in Mn SOD in type Ii cells of the proximal alveolar duct may reflect the ability of these cells to acquire tolerance and to resist further injury to r epeated ozone exposure.