Regulation of hepatic glycine catabolism by glucagon

Journal Article · Sat Feb 25 04:00:00 EST 1989 · J. Biol. Chem.; (United States)

OSTI ID:6464034

Jois, M; Hall, B; Fewer, K; Brosnan, J T

Glucagon stimulates 14CO2 production from (1-14C) glycine by isolated rat hepatocytes. Maximal stimulation (70%) of decarboxylation of glycine by hepatocytes was achieved when the concentration of glucagon in the medium reached 10 nM; half-maximal stimulation occurred at a concentration of about 2 nM. A lag period of 10 min was observed before the stimulation could be measured. Inclusion of beta-hydroxybutyrate (10 mM) or acetoacetate (10 mM) did not affect the magnitude of stimulation suggesting that the effects of glucagon were independent of mitochondrial redox state. Glucagon did not affect either the concentration or specific activity of intracellular glycine, thus excluding the possibilities that altered concentration or specific activity of intracellular glycine contributes to the observed stimulation. The stimulation of decarboxylation of glycine by glucagon was further studied by monitoring 14CO2 production from (1-14C)glycine by mitochondria isolated from rats previously injected with glucagon. Glycine decarboxylation was significantly stimulated in the mitochondria isolated from the glucagon-injected rats. We suggest that glucagon is a major regulator of hepatic glycine metabolism through the glycine cleavage enzyme system and may be responsible for the increased hepatic glycine removal observed in animals fed high-protein diets.

• Research Organization: Memorial Univ. of Newfoundland, St. John's (Canada)
• OSTI ID: 6464034
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 264:6; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACETOACETATES
AMINO ACIDS
ANIMAL CELLS
ANIMALS
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CATABOLISM
CHALCOGENIDES
CHEMICAL REACTIONS
COENZYMES
DECARBOXYLATION
DOSE-RESPONSE RELATIONSHIPS
ENZYMES
GLUCAGON
GLYCINE
HORMONES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIVER CELLS
MAMMALS
METABOLISM
NAD
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PEPTIDE HORMONES
PEPTIDES
POLYPEPTIDES
PROTEINS
RATS
REACTION KINETICS
REDOX REACTIONS
RODENTS
SOMATIC CELLS
TRACER TECHNIQUES
TRANSFERASES
VERTEBRATES