Responses of cytochrome P-450 isozymes of rat lung to in vivo exposure to ozone.

The effects of 2 weeks exposures of rats to 0.2 ppm O3 on pulmonary cytochrome P-450 isozymes were investigated. Two main types of cytochrome P-450 isozymes (cytochromes P-450FI and P-450FII) were separated from lung microsomes of control rats on an anion exchange cellulose column. Antibody raised against cytochrome P-450b, which is the main isozyme of liver obtained from phenobarbital-treated rats, cross-reacted with pulmonary cytochrome P-450FII, but not with cytochrome P-450FI. Ozone exposures caused increases in the content of both cytochromes P-450FI and P-450FII to the same extent two times greater than those of control rats without changes in immunological properties of these isozymes. No pulmonary cytochrome P-450 isozyme other than cytochromes P-450FI and P-450FII was observed in eluate through anion exchange column chromatography. These results indicate that increases in the content of pulmonary cytochrome P-450 of rats exposed to O3 can be ascribed to increase in constitutive types of the isozymes, but not to induction of other types of isozyme.