title: Relationship between survival times of rats exposed to lethal level of nitrogen dioxide and arylhydrocarbon hydroxylase activity in lungs.
abstract: A previous paper has shown that survival times of rats exposed to lethal levels of NO2 were prolonged by administration of enzyme-inducing agents prior to NO2 exposure, and that the survival time of female rats was longer than that of male rats. In order to investigate a mechanism on prolongation of survival times by administration of enzyme-inducing agents and on sex-difference, a relationship between survival times and microsomal enzyme activity in lungs of rats administered enzyme-inducing agents was examined. The survival times of rats exposed to 65 ppm NO2 were prolonged with increase of 3MC doses, and AHH activity in lungs of rats rose with increase of 3MC doses. A significant correlation between the survival time and AHH activity was observed. Induction of AHH activity of female rats administered 3MC was higher than that of male rats. NADPH-dependent cytochrome c reductase activity in lungs of male and female rats did not change with 3MC administration, and a significant relationship between the survival time and NADPH-dependent cytochrome c reductase activity was not observed. These results suggest that cytochrome P1-450 system in lung microsomes may have protective action against the toxicity of NO2.
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D004347:Drug Interactions; D005260:Female; D008168:Lung / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D009585:Nitrogen Dioxide / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors; D013997:Time Factors
chemical_list: D008748:Methylcholanthrene; D001189:Aryl Hydrocarbon Hydroxylases; D009585:Nitrogen Dioxide