Comparison of /sup 3/H-galactose and /sup 3/H-glucose as precursors of hepatic glycogen in control-fed rats
Labeling of hepatic glycogen derived from 3H-galactose and 3H-glucose was compared shortly after intravenous injection in control-fed rats. The rats were allowed to accumulate 5-8% glycogen prior to receiving label. Fifteen minutes to 2 hours after labeling, liver was excised and processed for routine light (LM) and electron microscopic (EM) radioautography (RAG) or biochemical analysis. After injection of 3H-galactose, LM-RAGs revealed that the percentage of heavily labeled hepatocytes increased from 37% after 15 minutes to 68% after 1 hour but showed no further increase after 2 hours. alpha-Amylase treatment removed most glycogen and incorporated label; thus few silver grains were observed, indicating little incorporation of label except into glycogen. EM-RAGs demonstrated that most label occurred where glycogen was located. Biochemical analysis showed initially a high blood level of label that rapidly plateaued at a reduced level by 5 minutes. Concomitantly, glycogen labeling determined by liquid scintillation counting reflected the increases observed in the RAGs. After injection of 3H-glucose, LM-RAGs revealed that only 12% of the hepatocytes were heavily labeled at 1 hour and 20% at 2 hours. In tissue treated with alpha-amylase, glycogen was depleted and label was close to background level at each interval observed. EM-RAGs showed most grains associated with glycogen deposits. Biochemically, blood levels of label persisted at a high level for 30 minutes and tissue levels increased slowly over the 2-hour period. This study shows that incorporation from 3H-galactose was more rapid than incorporation of 3H-glucose; however, label derived from both carbohydrates appeared to be incorporated mainly into glycogen.
- Research Organization:
- Univ. of Cincinnati College of Medicine, OH (USA)
- OSTI ID:
- 5767846
- Journal Information:
- Anat. Rec.; (United States), Vol. 224:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GALACTOSE
METABOLISM
GLUCOSE
GLYCOGEN
BIOSYNTHESIS
AMYLASE
AUTORADIOGRAPHY
COMPARATIVE EVALUATIONS
ELECTRON MICROSCOPY
INTRAVENOUS INJECTION
LIVER CELLS
PRECURSOR
RATS
SCINTILLATION COUNTING
TRITIUM COMPOUNDS
ALDEHYDES
ANIMAL CELLS
ANIMALS
CARBOHYDRATES
COUNTING TECHNIQUES
ENZYMES
GLYCOSYL HYDROLASES
HEXOSES
HYDROLASES
INJECTION
INTAKE
LABELLED COMPOUNDS
MAMMALS
MICROSCOPY
MONOSACCHARIDES
O-GLYCOSYL HYDROLASES
ORGANIC COMPOUNDS
POLYSACCHARIDES
RODENTS
SACCHARIDES
SOMATIC CELLS
SYNTHESIS
VERTEBRATES
550501* - Metabolism- Tracer Techniques