Studies on the mechanism of methylcholanthrene induction of enzyme activities of rat liver

Abstract

The administration in vivo of 3-methylcholanthrene (MC) increases the rate of leucine incorporation in a nuclei-free rat-liver homogenate system. Each subcellular fraction, the mitochondria, microsomes and supernatant fluid contribute to the increased activity in the MC preparation. The major part of the incorporation takes place in the microsomal fraction. The increase in incorporation in the microsomes from MC-treated rats is not secondary to changes in the concentration of magnesium ion or GTP. Parallel changes in the activity of the supernatant fluid appear due to a more adequate maintenance of proper GTP levels in the supernatant from MC-treated rats.