|
|
||||||||
1 Departments of Pediatric Gastroenterology and 2 Clinical Chemistry and Pediatrics, VU University Medical Center, 1007 MB Amsterdam; 4 Laboratory for Metabolic Diseases, University Children's Hospital, 3508 AB Utrecht; and 5 Laboratory for Metabolic Diseases, Department of Pediatrics, University Hospital Groningen, 9700 RB Groningen, The Netherlands; and 3 Robert Schwartz, M.D., Center for Metabolism and Nutrition, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44109
We studied the role of lactate in
gluconeogenesis (GNG) during exercise in untrained fasting humans.
During the final hour of a 4-h cycle exercise at 33-34% maximal
O2 uptake, seven subjects received, in random order, either
a sodium lactate infusion (60 µmol · kg
1 · min
1)
or an isomolar sodium bicarbonate infusion. The contribution of lactate
to gluconeogenic glucose was quantified by measuring 2H
incorporation into glucose after body water was labeled with deuterium
oxide, and glucose rate of appearance (Ra) was measured by
[6,6-2H2]glucose dilution. Infusion of
lactate increased lactate concentration to 4.4 ± 0.6 mM
(mean ± SE). Exercise induced a decrease in blood glucose
concentration from 5.0 ± 0.2 to 4.2 ± 0.3 mM
(P < 0.05); lactate infusion abolished this decrease
(5.0 ± 0.3 mM; P < 0.001) and increased glucose
Ra compared with bicarbonate infusion (P < 0.05). Lactate infusion increased both GNG from lactate (29 ± 4 to 46 ± 4% of glucose Ra, P < 0.001) and total GNG. We conclude that lactate infusion during
low-intensity exercise in fasting humans 1) increased GNG
from lactate and 2) increased glucose production, thus
increasing the blood glucose concentration. These results indicate that
GNG capacity is available in humans after an overnight fast and can be
used to sustain blood glucose levels during low-intensity exercise when
lactate, a known precursor of GNG, is available at elevated plasma levels.
lactate; hyperlactatemia; stable isotopes
This article has been cited by other articles:
![]() |
H. B. Nielsen, M. A. Febbraio, P. Ott, P. Krustrup, and N. H. Secher Hepatic lactate uptake versus leg lactate output during exercise in humans J Appl Physiol, October 1, 2007; 103(4): 1227 - 1233. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Iwashita, P. Williams, K. Jabbour, T. Ueda, H. Kobayashi, S. Baier, and P. J. Flakoll Impact of glutamine supplementation on glucose homeostasis during and after exercise J Appl Physiol, November 1, 2005; 99(5): 1858 - 1865. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. F. Miller, M. I. Lindinger, J. A. Fattor, K. A. Jacobs, P. J. LeBlanc, M. Duong, G. J. F. Heigenhauser, and G. A. Brooks Hematological and acid-base changes in men during prolonged exercise with and without sodium-lactate infusion J Appl Physiol, March 1, 2005; 98(3): 856 - 865. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |