Methyl red azo-reductase and its induction by 3-methylcholanthrene in the liver of different species

Abstract

1. Methyl red azo-reductase activity in the liver cytosol of mouse and sheep was considerably less than in the rat, guinea-pig, rabbit and hamster. In the mouse, the total activity of this soluble enzyme to reduce methyl red was only 4% of that found in rat.

2. Species variation in methyl red azo-reductase of microsomes was relatively small compared to that of the cytosol.

3. Azo-reductase in the cytosol of mouse liver also differed from that of the rat in its resistance to the inductive effects of 3-methylcholanthrene.