Early glycogenolysis and late glycogenesis in human liver after
intravenous administration of galactose.
Fried, Ronald, Nicolau Beckmann, Ulrich Keller, Ronald Ninnis, Georg
Stalder, and Joachim Seelig.
Department of Internal Medicine, University Hospital, Petersgraben
2, CH-4031 Basel, and MR Center and Biocenter, Klingelbergstr. 70,
CH-4056 Basle, Switzerland, Present address: Biophysics Unit,
Preclinical Research, Sandoz Pharma Ltd., P.O. Box, CH-4002 Basle,
Switzerland
APStracts 2:0147G, 1995.
Galactose is incorporated by a different metabolic pathway than
glucose. Its contribution to glycogen synthesis has not been studied
in man. We administered galactose (0.5 g/kg) intravenously to
overnight-fasted normal human volunteers and examined its effects on
hepatic glycogen synthesis and hepatic glucose output (HGO). Hepatic
glycogenesis was assessed non-invasively, determining glycogen
concentration by 13C-magnetic resonance spectroscopy (MRS) and liver
volume by magnetic resonance imaging. HGO was determined by [6,6
-2H2]glucose and gluconeogenesis calculated by adding the amount of
hepatic glycogenesis to the HGO. After galactose administration,
liver glycogen concentration (baseline 254+/-11 mmol/L) decreased in
the first 45 min to 207+/-15 mmol/L (p<0.05) and increased
thereafter to 313+/-7 mmol/L (p< 0.01). Net hepatic glycogenesis
was 101+/-12 mmol over 150 minutes. HGO (baseline 14.3+/-1.9
[mu]mol*kg-1*min-1) increased threefold in the first 15 min and then
returned to baseline. The average rate of gluconeogenesis was 12.3
[mu]mol*kg-1 *min-1. Intravenous galactose leads to an increase in
hepatic glycogen and hepatic glucose output in normal man.
Competitive inhibition of UDP-glucose pyrophosphorylase by UDP
-galactose could explain the apparent glycogenolysis observed early
after galactose administration. 13C-MRS in combination with a stable
isotope tracer is a non-invasive and safe method to study hepatic
carbohydrate metabolism in humans.
Received 12 April 1995; accepted in final form 7 July 1995.
APS Manuscript Number G151-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 July 1995.