Fructose effect to enhance liver glycogen deposition is due to inhibition of glycogenolysis

Conference · Fri May 01 04:00:00 EDT 1987 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5941665

Youn, J; Kaslow, H; Bergman, R

The effect of fructose on glycogen degradation was examined by measuring flux of (/sup 14/C) from prelabeled glycogen in perfused rat livers. During 2 h refeeding of fasted rats hepatic glycogen was labeled by injection of (U /sup 14/C) galactose (0.1 mg and 0.02 ..mu..Ci/g of body weight). Refed livers were perfused for 30 min with glucose only (10 mM) and for 60 min with glucose (10 mM) without (n=5) or with fructose (1, 2, 10 mM; n=5 for each). With fructose, label production immediately declined and remained suppressed through the end of perfusion (P < 0.05). Suppression was dose-dependent: steady state label production was suppressed 45, 64, and 72% by 1, 2, and 10 mM fructose (P < 0.0001), without significant changes in glycogen synthase or phosphorylase. These results suggest the existence of allosteric inhibition of phosphorylase in the presence of fructose. Fructose 1-phosphate (F1P) accumulated in proportion to fructose (0.11 +/- 0.01 without fructose, 0.86 +/- 0.03, 1.81 +/- 0.18, and 8.23 +/- 0.6 ..mu..moles/g of liver with 1, 2, and 10 mM fructose. Maximum inhibition of phosphorylase was 82%; FIP concentration for half inhibition was 0.57 ..mu..moles/g of liver, well within the concentration of F1P attained in refeeding. Fructose enhances net glycogen synthesis in liver by suppressing glycogenolysis and the suppression is presumably caused by allosteric inhibition of phosphorylase by F1P.

• Research Organization: Univ. of Southern California School of Medicine, Los Angeles
• OSTI ID: 5941665
• Report Number(s): CONF-870644-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 46:6
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALDEHYDES
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
BODY
CARBOHYDRATES
CARBON 14 COMPOUNDS
DIGESTIVE SYSTEM
DOSE-RESPONSE RELATIONSHIPS
ENZYMES
FRUCTOSE
GALACTOSE
GLANDS
GLYCOGEN
GLYCOLYSIS
HEXOSES
INHIBITION
ISOTOPE APPLICATIONS
KETONES
KINETICS
LABELLED COMPOUNDS
LIVER
MAMMALS
METABOLISM
MONOSACCHARIDES
ORGANIC COMPOUNDS
ORGANS
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
POLYSACCHARIDES
RATS
REACTION KINETICS
RODENTS
SACCHARIDES
SYNTHESIS
TRACER TECHNIQUES
TRANSFERASES
VERTEBRATES