Hepatic glycogen in humans. II. Gluconeogenetic formation after oral and intravenous glucose
- Univ. of Western Ontario, London (Canada)
The amount of glycogen that is formed by gluconeogenetic pathways during glucose loading was quantitated in human subjects. Oral glucose loading was compared with its intravenous administration. Overnight-fasted subjects received a constant infusion or (3-{sup 3}H)glucose and a marker for gluconeogenesis, (U-{sup 14}C)lactate or sodium ({sup 14}C)bicarbonate ({sup 14}C)bicarbonate. An unlabeled glucose load was then administered. Postabsorptively, or after glucose infusion was terminated, a third tracer ((6-{sup 3}H)glucose) infusion was initiated along with a three-step glucagon infusion. Without correcting for background stimulation of ({sup 14}C)glucose production or for dilution of {sup 14}C with citric acid cycle carbon in the oxaloacetate pool, the amount of glycogen mobilized by the glucagon infusion that was produced by gluconeogenesis during oral glucose loading was 2.9 +/- 0.7 g calculated from (U-{sup 14}C)-lactate incorporation and 7.4 +/- 1.3 g calculated using ({sup 14}C)bicarbonate as a gluconeogenetic marker. During intravenous glucose administration the latter measurement also yielded 7.2 +/- 1.1 g. When the two corrections above are applied, the respective quantities became 5.3 +/- 1.7 g for (U-{sup 14}C)lactate as tracer and 14.7 +/- 4.3 and 13.9 +/- 3.6 g for oral and intravenous glucose with ({sup 14}C)bicarbonate as tracer (P less than 0.05, vs. ({sup 14}C)-lactate as tracer). When (2-{sup 14}C)acetate was infused, the same amount of label was incorporated into mobilized glycogen regardless of which route of glucose administration was used. Comparison with previous data also suggests that {sup 14}CO{sub 2} is a potentially useful marker for the gluconeogenetic process in vivo.
- OSTI ID:
- 5477536
- Journal Information:
- American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 257; ISSN 0002-9513; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ACETATES
ACID CARBONATES
ALDEHYDES
ANIMALS
BIOLOGICAL MARKERS
BIOLOGICAL MATERIALS
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
BLOOD
BODY
BODY FLUIDS
CARBOHYDRATES
CARBON 14 COMPOUNDS
CARBOXYLIC ACID SALTS
DIET
DIGESTIVE SYSTEM
FASTING
GLANDS
GLUCOSE
GLYCOGEN
HEXOSES
HYDROGEN COMPOUNDS
INJECTION
INTAKE
INTRAVENOUS INJECTION
ISOTOPE APPLICATIONS
ISOTOPE DILUTION
LABELLED COMPOUNDS
LACTATES
LIVER
MAMMALS
MAN
MATERIALS
METABOLISM
MONOSACCHARIDES
ORAL ADMINISTRATION
ORGANIC COMPOUNDS
ORGANS
POLYSACCHARIDES
PRIMATES
SACCHARIDES
SYNTHESIS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES