Glycogen metabolizing enzyme activities in the developing rat liver.

1. The glycogen content of rat liver increased prenatally and dramatically decreased after the birth. 2. Glycogen synthase and glycogen phosphorylase activities increased prenatally, declined at 12 hr after birth and then again increased. 3. Phosphorylase kinase activities did not significantly change prenatally but steadily increased after the birth. 4. Protein kinase activities (units/mg liver) did not change prenatally but slightly increased after the birth. 5. Phosphoprotein phosphatase activities using phosphorylase a and histone as substrates dramatically increased at birth and then decreased after 24 hr of the birth.