The in vitro synthesis of glycogen in the diaphragms of normal and alloxan-diabetic rats

Abstract

Glycogen synthesis and glycogenolysis by rat diaphragm and liver were studied in vitro. K inhibited synthesis from added glucose and favored glycogenolysis in the rat diaphragm but was essential for synthesis in rat liver slices. Adrenaline completely inhibited synthesis and favored glycogenolysis, and this effect was abolished by ergotamine. Insulin favored synthesis but its action was abolished by addition of serum. When alloxan-diabetic rats were used, however, incubation with diabetic serum decreased glycogen synthesis by both diabetic and normal diaphragm, and this effect could be reversed by the addition of insulin or a concentrate of normal serum. As these differences were not detected in salt buffer solns., it is suggested that metabolic changes of tissues in vitro may become manifest only in a correspondingly changed medium.