QUANTITATIVE HISTOLOGY AND CYTOCHROME-P-450 IMMUNOCYTOCHEMISTRY OF THE LUNG PARENCHYMA FOLLOWING 6 MONTHS OF EXPOSURE OF STRAIN A J MICE TOCIGARETTE SIDESTREAM SMOKE/

Male strain A/J mice were exposed for 6 h/day, 5 days/wk to aged and d iluted cigarette sidestream smoke (ADSS) at a chamber concentration of 4 mg/m(3) of total suspended particulate matter (TSP). After 6 mo, th e lungs were examined for altered expression of cytochrome P-450 isozy mes and for differences in total alveolar tissue volume or surface are a, as well as changes in the numbers of epithelial type II cells and a lveolar macrophages. Morphologic measurements showed no statistically significant differences for the air, alveolar tissue, or capillary vol umes of the lungs or changes in the total number of epithelial type II cells or alveolar macrophages. In contrast, cytochrome P-4501A1 was e levated in the lungs of ADSS-exposed animals and localized in capillar y endothelial cells. CYP2B1 was present in airway epithelial cells as well as in epithelial cells throughout the lung parenchyma, but its di stribution was not changed by ADSS exposure. Isozyme CYP2E1 was also f ound in airway epithelial cells, but not in the lung parenchyma, with no differences noted between ADSS exposed animals and controls. CYP2F2 was found in the bronchiolar Clara cells and in type II cells located within the alveolar parenchyma, bur was also unchanged. It is conclud ed that chronic exposure to cigarette ADSS at 4 mg/m(3) of TSP produce s no changes in alveolar macrophages or epithelial type II cells in mo use lung but increases the expression of cytochrome P4501A1.