Glucose-C14 incorporation into extractable and residual glycogen by liver slices.

Abstract Glucose-C 14 incubated with rabbit or rat liver slices in Hastings medium incorporates into the two glycogen fractions isolated by trichloroacetic acid solution. Specific activity of extractable glycogen is always two or three times greater than specific activity of residual glycogen. Incorporation-time curve is a straight line for both glycogen fractions up to 1 hr. of incubation. Fasting does not modify incorporation of glucose-C 14 into extractable glycogen but stimulates it in residual glycogen. Previous incubation of the slices in Krebs medium increases the incorporation of glucose-C 14 into residual glycogen, but its incorporation into extractable glycogen is almost abolished.