Determination of Glycogen in Tissues* by Melville Sahyun

The purpose of the present paper is to present some simplifying modifications of Pfltiger’s method (1) for the estimation of glycogen, that render it available for small amounts of tissue. The suggested modifications involve (a) shortening of the time necessary to hydrolyze the tissue with strong alkali, (b) facilitation of the separation of the glycogen by precipitating it in the presence of charcoal and centrifuging, (c) hydrolysis of the separated glycogen for a shorter time than customary, and (d) the substitution of sulfuric acid for hydrochloric acid to avoid the introduction of chlorides. (a) Less than the 2 hours of hydrolysis with strong potassium hydroxide recommended by Pfliiger (1) has been found sufficient by Schiindorff and coworkers (2) who using 30 per cent potassium hydroxide found 30 minutes sufficient for liver and muscle, provided the flasks were shaken thoroughly every 5 to 10 minutes. Bierry and Gruzewska (3) obtained good results by autoclaving at 120” for 30 minutes with 35 per cent potassium hydroxide. The time recommended in the writer’s procedure is 30 to 40 minutes. (b) Pfltiger (4) found the precipitation of glycogen by alcohol from its solutions in strong alkali may take place so slowly that there is danger of losses in its estimation. The procedure recommended in the present paper avoids this danger by adsorbing the glycogen on activated charcoal which is found not to interfere with the subsequent sugar determination. Moreover, when the washed glycogen is hydrolyzed, the filtration and clarification of