The effect of the ionic environment on the synthesis of glycogen from glucose in rat liver slices.

The effect of the ionic environment of the incubating medium upon glycogen formation by liver slices was first reported by Ostern, Herbert, and Holmes (1). Using rabbit liver slices, they found that, aerobically, calcium stimulated glycogen formation in a modified Ringer’s medium containing 1 per cent glucose. Addition of phosphate to this medium resuhed in a decrease in glycogen synthesis. The effect of calcium on glycogenesis by rabbit liver slices has been confirmed in this laboratory. In agreement with other investigators, however, little glycogen synthesis from glucose could be obtained in the presence of rat liver slices incubated in a calcium-containing Ringer’s solution. In experiments previously reported, a medium simulating the cationic composition of the intracellular fluid, i.e. high in potassium and magnesium, was fourid to promote glycogenesis by rat liver slices (2). Since the publication of these preliminary experiments, the ionic composition of the incubating medium has been systematically varied in order to determine the rBle which different inorganic ions play in glycogen synthesis from glucose by rat liver slices. It is the purpose of this communication to report these experiments.