Circadian changes of cytochrome P-450-dependent monooxygenase system in the rat liver.

Abstract

Circadian changes in cytochrome P-450 and cytochrome b5 content and activity of NADPH-cytochrome P-450 and NADH-cytochrome b5 reductases have been studied in rat liver microsomes in season autumn. The obtained results indicate, that cytochrome P-450 in 6-month-old animals shows 12 h rhythm, but in older ones 24 h rhythm. NADPH-cytochrome P-450 reductase activity shows 24 h rhythm in oldest animals only. Cytochrome b5 and its reductase has 24 h rhythm in all examined groups of rats.