The glucose-galactose paradox in neonatal murine hepatic glycogen synthesis

Journal Article · Wed Nov 01 00:00:00 EST 1989 · American Journal of Physiology; (USA)

OSTI ID:5074655

Kunst, C; Kliegman, R; Trindade, C ^[1]

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1. Case Western Reserve Univ. at Rainbow Babies and Childrens Hospital, Cleveland, OH (USA)

In adults glucose incorporation to glycogen is indirect after recycling from lactate. In neonates galactose entry to glycogen exceeds that for glucose, but the pathway is unknown. The pathway of hexose incorporation to glycogen was studied in 5-7-day-old rats and 6-h-old rats injected intraperitoneally (IP) with either double-labeled (6-3H)glucose (nonrecycling), (U-14C)glucose (recycling), or (6-3H)glucose and (U-14C)galactose in saline. In another group of pups, 1 g/kg of glucose or galactose was administered in addition to tracers to determine glycemia and net glycogen synthesis between 15 and 180 min after injection. Blood glucose increased from 3.4 +/- 0.4 to 8.5 +/- 1.5 mM in 5-7-day-old pups in response to IP glucose; there was no glycemic response to galactose, although galactose levels increased from 0.5 to 6.3 mM at 15 min. Hepatic glycogen increased after IP glucose from 14 +/- 2 at 15 min to 30 +/- 3 at 120 min (P less than 0.01), whereas after IP galactose glycogen was 44 +/- 6 mumol/g at 120 min (P less than 0.05). After IP glucose, 3H and 14C disintegration per minute in glycogen increased slowly with 14C exceeding 3H at 120 and 180 min. In contrast IP (14C)galactose resulted in a much greater peak of 14C incorporation into glycogen. The ratio of 3H to 14C in glycogen relative to the injectate after IP glucose decreased from 0.69 +/- 0.12 to 0.36 +/- 0.03 (P less than 0.01) between 15 to 180 min, whereas the ratio after galactose was 0.20 +/- 0.007 to 0.15 +/- 0.02 at these times. The 6-h-old pups also demonstrated augmented incorporation of (14C)galactose in glycogen relative to (3H-14C)glucose. In contrast to 5-7-day-old pups there was no evidence of glucose recycling in 6-h-old pups. In conclusion galactose entry into glycogen exceeds that for glucose and is not dependent on recycling.

• OSTI ID: 5074655
• Journal Information: American Journal of Physiology; (USA), Vol. 257; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
GLYCOGEN
BIOSYNTHESIS
CARBON 14 COMPOUNDS
GALACTOSE
GLUCOSE
LIVER
NEONATES
RATS
TRACER TECHNIQUES
ALDEHYDES
ANIMALS
BODY
CARBOHYDRATES
DIGESTIVE SYSTEM
GLANDS
HEXOSES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
MONOSACCHARIDES
ORGANIC COMPOUNDS
ORGANS
POLYSACCHARIDES
RODENTS
SACCHARIDES
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques