Free and fixed glycogen in rat muscle

Abstract

The occurrence of free and fixed glycogen in the gastrocnemius muscle of the rat was studied. Considerable individual differences were observed in the ratio, free: fixed glycogen. Identical values, however, were found for free and fixed glycogen respectively, in the right and left gastrocnemius muscle of the rat. Performance of work alters the ratio free: fixed glycogen in the gastrocnemius muscle. Two different methods of extraction, i.e. with trichloroacetic acid and with water containing ethylenediaminetetraacetic acid to prevent glycogenolysis, yielded the same values for the 2 glycogen fractions respectively. It is concluded that the fixed glycogen is probably a physiological entity and not an artifact.