Abstract

The effects of phenobarbital and 3-methylcholanthrene on amino acid incorporation into rat liver chromosomal proteins in vivo were studied. Although both drugs stimulated incorporation into histones and non-histone chromosomal proteins, the results of dual-isotope experiments revealed that the increases were not selective for any of the major non-histone chromosomal protein fractions. Rather, incorporation into all these fractions was apparently stimulated uniformly. This nonselective stimulation of incorporation may reflect drug-induced increases in amino acid incorporation preceding mitotic activity and liver growth.