Stimulation of hepatic RNA synthesis by phenobarbital

Administration of phenobarbital in rats is followed by an in vitro stimulation of hepatic ribosomal protein synthesis. The increase of polyribosomes which is also observed is paralleled by a phenobarbital-dependent enhancement of uridine incorporation into ribonucleic acids. Sedimentation of either ribosomes or ribosomal RNA extracted from ribosomal subunits through sucrose gradients reveals stimulation by phenobarbital of 3H-uridine incorporation into messenger RNA as well as into ribosomal RNA. These experiments together with the findings of stimulation of RNA polymerase activity and blockade of the effects of phenobarbital by the administration of Actinomycin D indicate a primary action of phenobarbital on RNA synthesis.