The effects of some tobacco smoke constituents on foreign compound metabolism in the cat and the rat.

The effects of chronic nicotine administration on its own metabolism have been studied in the cat and the rat. Nicotine administration caused an increase in the in vitro metabolism in the liver of both species and in cat kidney. Cotinine production from nicotine was enhanced in both species by pretreatment with nicotine. The magnitude of the increase in enzyme activity was relatively small but of the same order as that produced, in the rat, by phenobarbital treatment. 3-methylcholanthrene pretreatment stimulated rat liver nicotine metabolism but was without effect on cotinine production. Chronic exposure of rats to relatively low levels of carbon monoxide inhibited the in vitro aryl hydrocarbon hydroxylase activity but did not affect nicotine metabolism. The data are discussed in relation to the observed enzyme inductive effects of tobacco smoke.