[Effect of cold stress on the concentration and activity of rat liver microsomal cytochrome [P-450]

The level of cytochromes P-450 and b5 in rat liver microsomes was studied at varying times after a short-term cold stress. The level of cytochromes was found to be reduced 24-72 hours after the exposure. Complete normalization of the level of cytochromes was recorded on the 9th day after the exposure. Variation of demethylase activity and the ratio of two different forms of cytochrome P-450 were also examined after the exposure to stress. A possible relationship between the decreased P450 level and intensification of lipid peroxidation in the rat liver is discussed.