The effect of chronic ozone exposure on lung benzo(a)pyrene oxidase, benzphetamine demethylase and monoamine oxidase.

Adult male Fischer 344 rats were exposed either to clean air or to a mixture of clean air and 0.5ppm ozone for up to one year. These populations were sampled after three and six months and when the exposure was completed. The activity of several oxidative enzymes in these rat lungs were compared. Although there was no significant increase in the ability of pulmonary microsomes to oxidize benzo[alpha]pyrene after three months of exposure to ozone, this activity and the oxidative demethylation of benzphetamine were increased after six months and a year of exposure. Aside from these enzymatic changes, electrophoretic analysis indicated that the microsomes from ozone exposed rats were enriched with a protein with an apparent molecular weight of 68,000. The activity of the two isoenzymic forms of monoamine oxidase, MAO A and MAO B, were also measured, and neither activity was affected by the ozone exposure.