Effects of storage conditions in vitro on the assay of chick liver glycogen.

1. The reproducibility of an enzymic method for assaying chick liver glycogen was found to be +/- 1.6%. 2. Storage of liver at either -21 or -70 degrees C for up to 4 weeks, after freezing in liquid nitrogen, had no significant effect on glycogen concentration. However, the concentration of free glucose increased by about 50% during this time. 3. Storage of liver in ice-cold saline for up to 3 h proved unsatisfactory because of a significant loss of glycogen. 4. There was no significant difference in immediate glycogen concentration in liver tissue that was freeze-clamped, frozen in liquid nitrogen or collected into ice-cold saline. The free glucose concentration was higher, when estimated immediately after, with the latter two methods of collection of liver tissue.