Role of Cyclic Adenosine 3’, 5’-Monophosphate in the Induction of Hepatic Enzymes II. EFFECT OF N6 ,02’-DIBUTYRYL CYCLIC ADENOSINE 3’, 5’-MONOPHOSPHATE ON THE KINETICS OF RIBONUCLEIC ACID SYNTHESIS IN PURIFIED RAT LIVER NUCLEI*

iV6,0P’-Dibutyryl cyclic 3’,5’-AMP stimulated the rate of incorporation of 3H-uridine into nuclear RNA in two consecutive waves without affecting the accumulation of labeled uridine in the free pool of the nuclei. N6,02’-Dibutyryl cyclic 3’,5’-AMP exerted its maximal effect at a concentration of 10e4 M. At this concentration the cyclic nucleotide had no effect on the rate of nuclear ATP synthesis. The first wave of RNA synthesis consisted mainly of 45,32, and 18 S ribosomal RNA and its synthesis was fully inhibited by 0.2 pg per ml of actinomycin D. In contrast the second wave of RNA synthesis consisted mainly of heterogeneous RNA ranging from 7 to 18 S and its synthesis was completely inhibited by 0.04 pg per ml of cr-amanitin. Both the Mg++-low salt and the Mn++-high salt-stimulated RNA polymerases showed an increased activity in the presence of 10V4 M IV, 02’-dibutyryl cyclic AMP.