ADRENAL CORTICOSTEROID INVOLVEMENT IN CONTROL OF PHOSPHORYLASE IN MUSCLE

Adrenalectomy does not result in any change in the levels of active or inactive muscle glycogen phosphorylase. However, in adrenalectomized rats administration of epinephrine or cyclic-AMP is not followed by activation of the enzyme. Hydrocortisone replacement therapy results in a return of the activation capabilities of epinephrine and cyclic-AMP. Hydrocortisone treatment also results in an increase in phosphorylase to twice normal levels. We propose that adrenal corticosteroids play a role in the conversion of inactive to active phosphorylase and in the regulation of phosphorylase synthesis. © 1969.