Enzymic analysis of rat liver carbohydrate: Glucose and oligoglucoside contents as additional indices in metabolic studies
✍ Scribed by John A. Johnson; Ramon M. Fusaro
- Publisher
- Elsevier Science
- Year
- 1967
- Tongue
- English
- Weight
- 716 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
We recently described a method for the direct enzymic (DE)2 assay of glycogen in liver homogenate (1). The unique features of this technique are: (1) Glycogen content is determined without prior isolation and purification of the carbohydrate.
(2) Oligoglucosides (OG) are detected as glycogen. (3) Tissue glucose content is determined simultaneously. In order to reconcile the difference in glycogen yield between the enzymic technique and that based on ethanol precipitation of glycogen from KOH digests (KOH glycogen), it was necessary to develop an independent assay for OG. The determination of glucose, OG, and glycogen contents of liver homogenates obtained under a variety of conditions led to the conclusion that the relative quantities of these fractions provide useful indices for the investigation of in uivo and in vitro carbohydrate metabolism of liver. In particular, the practical problem of obtaining glycogen values which accurately reflect the carbohydrate content of liver in the intact animal can be examined in detail.
An obvious source of error in the determination of liver glycogen content is the nonuniform distribution of carbohydrate within the organ. Many investigators, rather than employ the cumbersome technique of processing the entire organ, analyze a relatively large piece of each test specimen, assuming that sampling error will be minimized by examining a large number of specimens in each experimental group. A more reliable alternative is the application of a technique (2) which converts an intact rat liver to a homogeneous frozen powder, small portions of which can be analyzed for average carbohydrate content of the specimen.
A second type of error in carbohydrate analysis results from unavoid-'This result is not surprising in view of a current report by Hanlon et al. CAnal. Biochem. 16, 225 (1966)l in which they state that tris buffer strongly binds divalent mercury ion.