Selective enhancement of xenobiotic metabolizing systems of rat lungs by prolonged exposure to ozone

Journal Article · Wed Apr 01 04:00:00 EST 1987 · Environ. Res.; (United States)

DOI:https://doi.org/10.1016/S0013-9351(87)80210-4· OSTI ID:6326527

Takahashi, Y; Miura, T

Male Wistar rats were exposed to 0.2 and 0.4 ppm O/sub 3/ for 4, 8, and 12 weeks and to 0.1 and 0.2 ppm O/sub 3/ for 4 weeks to examine the effects of prolonged exposure to O/sub 3/ on the xenobiotic metabolizing systems in the lung. Exposures to 0.2 and 0.4 ppm O/sub 3/ caused a significant increase in the NADPH-cytochrome P-450 reductase activity and cytochrome P-450 content in a dose-dependent manner during 4-12 weeks, whereas NADH-cytochrome b5 reductase was not altered. After 12 weeks of exposure to 0.4 ppm O/sub 3/, NADPH-cytochrome P-450 reductase and cytochrome P-450 reached a maximum showing 138 and 221% those of the control levels, respectively. At 0.1 ppm O/sub 3/, the cytochrome P-450 content still increased significantly to 152% that of the control on the fourth week. In parallel to the increment of cytochrome P-450 benzo(a)pyrene hydroxylase and 7-ethoxycoumarin O-deethylase increased significantly during 4-12 weeks of exposures to 0.2 and 0.4 ppm O/sub 3/. After a 4-week exposure to 0.1 and 0.2 ppm O/sub 3/, benzphetamine N-demethylase increased to the largest degree among the enzymes metabolizing four kinds of xenobiotics examined. 7-Ethoxycoumarin O-deethylase also increased significantly but of smaller magnitude, whereas coumarin hydroxylase was not affected. These results show that prolonged exposures to 0.1-0.4 ppm O/sub 3/ persistently enhance pulmonary cytochrome P-450 systems. It is also suggested that some isozyme(s) of pulmonary cytochrome P-450, especially that catalyzing benzphetamine N-demethylation, are preferentially increased by exposure to low levels of O/sub 3/.

• Research Organization: National Institute for Environmental Studies, Ibaraki, Japan
• OSTI ID: 6326527
• Journal Information: Environ. Res.; (United States), Journal Name: Environ. Res.; (United States) Vol. 2; ISSN ENVRA
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMALS
BODY
CELL CONSTITUENTS
CYTOCHROME OXIDASE
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ENZYME ACTIVITY
ENZYMES
HAEM DEHYDROGENASES
LUNGS
MAMMALS
MICROSOMES
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
OXIDOREDUCTASES
OZONE
PROTEINS
RATS
RESPIRATORY SYSTEM
RODENTS
TOXICITY
VERTEBRATES