Glucagon Stimulation of DNA Synthesis in Neonatal‐Rat Liver: Evidence for a DNAase‐Mediated Effect

The incorporation of [³H]thymidine into DNA in foetal‐rat‐liver slices was shown to be enhanced in the presence of glucagon. Under similar conditions the activity of enzymes involved in the incorporation pathway remains unaltered. The results of this study reveal that the polymerizing activity associated with the “nuclear” pellet of foetal rat liver prefers denaturated primer in contrast to a similar extract from regenerating adult rat liver. The addition of pancreatic deoxyribonuclease to foetal‐rat‐liver homogenates can enhance [³H]thymidine incorporation, and suggests that an alteration in the state of the primer can influence the activity of DNA polymerase. The presence of glucagon is shown to increase deoxyribonuclease activity in foetal homogenates and it is proposed that the hormone can influence the rate of [³H]thymidine incorporation in this system through an alteration in the state of the primer.