The Mechanism of Epinephrine Action. I. the Influence of Epinephrine on the Carbohydrate Metabolism of Fasting Rats, with a Note on New Formation of Carbohydrates. by Carl F. Cori

Dudley and Marrian (1) were the first to show that liver glycogen disappears in fasting animals when insulin is injected. Cannon, McIver, and Bliss (2) found that insulin hypoglycemia leads to an increased discharge of epinephrine. Furthermore, there was general agreement that epinephrine mobilizes liver glycogen. By linking these three facts together, a strong case was made out for the asSumption that the disappearance of liver glycogen in insulinized animals was due to the discharge of epinephrine. This assumption is contradicted by the recent observation (3) that insulin mobilizes liver glycogen in adrenalectomized animals; that is, in animals with an abolished or at least strongly reduced epinephrine secretion. A decrease in liver glycogen in adrenalectomized rats following insulin injections has been found independently by Artundo (4). The results of Cannon and his collaborators and of other investigators are accepted as evidence that insulin evokes an increased discharge of epinephrine, while the observations on adrenalectomized animals referred to above are taken as evidence that the disappearance of liver glycogen following insulin injections is not connected with this increased release of epinephrine. In view of this it was difficult to see how the antagonistic action of insulin and epinephrine on blood sugar was brought about. The following question presented itself. If insulin alone is capable of a rapid glycogen mobilization in the liver, and if epinephrine has its chief point of attack on liver glycogen, how does epinephrine antagonize the insulin hypoglycemia? There