Journal of Applied Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

J Appl Physiol 93: 233-241, 2002; doi:10.1152/japplphysiol.01050.2001
8750-7587/02 $5.00
This Article
Right arrow Full Text Free
Right arrow Full Text (PDF) Free
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (12)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Trimmer, J. K.
Right arrow Articles by Brooks, G. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Trimmer, J. K.
Right arrow Articles by Brooks, G. A.
Vol. 93, Issue 1, 233-241, July 2002

Measurement of gluconeogenesis in exercising men by mass isotopomer distribution analysis

Jeff K. Trimmer1, Jean-Marc Schwarz2, Gretchen A. Casazza1, Michael A. Horning1, Nestor Rodriguez2, and George A. Brooks1

Departments of 1 Integrative Biology and 2 Nutritional Sciences, University of California, Berkeley, California 94720

We evaluated the hypothesis that coordinated adjustments in absolute rates of gluconeogenesis (GNGab) and hepatic glycogenolysis (Gly) would maintain euglycemia and match glucose production (GP) to peripheral utilization during rest and exercise. Specifically, we evaluated the extent to which gradations in exercise power output would affect the contribution of GNGab to GP. For these purposes, we employed mass isotopomer distribution analysis (MIDA) and isotope-dilution techniques on eight postabsorptive (PA) endurance-trained men during 90 min of leg cycle ergometry at 45 and 65% peak O2 consumption (VO2 peak; moderate and hard intensities, respectively) and the preceding rest period. GP was constant in resting subjects, whereas the fraction from GNG (fGNG) increased over time during rest (22.3 ± 0.9% at 11.25 h PA vs. 25.6 ± 0.9% at 12.0 h PA, P < 0.05). In the transition from rest to exercise, GP increased in an intensity-dependent manner (rest, 2.0 ± 0.1; 45%, 4.0 ± 0.4; 65%, 5.84 ± 0.64 mg · kg-1 · min-1, P < 0.05), although glucose rate of disappearance exceeded rate of appearance during the last 30 min of exercise at 65% VO2 peak. Compared with rest, increases in GP were sustained by 92 and 135% increments in GNGab during moderate- and hard-intensity exercises, respectively. Correspondingly, Gly (calculated as the difference between GP and MIDA-measured GNGab) increased 100 and 203% over rest during the two exercise intensities. During moderate-intensity exercise, fGNG was the same as at rest; however, during the harder exercise fGNG decreased significantly to account for only 21% of GP. The highest sustained GNGab observed in these trials on PA men was 1.24 ± 0.3 mg · kg-1 · min-1. We conclude that, after an overnight fast, 1) absolute GNG rates increased with intensity of effort despite a reduced fGNG at 65% VO2 peak, 2) during exercise Gly is more responsible than GNGab for maintaining GP, and 3) in 12-h fasted men, neither increased Gly or GNGab nor was their combination able to maintain euglycemia during prolonged hard (65% VO2 peak) exercise.

glycogenolysis; glucose kinetics; glycerol; exertion; glucose production


This article has been cited by other articles:


Home page
 J. Biol. Chem.Home page
A. R. Wende, P. J. Schaeffer, G. J. Parker, C. Zechner, D.-H. Han, M. M. Chen, C. R. Hancock, J. J. Lehman, J. M. Huss, D. A. McClain, et al.
A Role for the Transcriptional Coactivator PGC-1{alpha} in Muscle Refueling
J. Biol. Chem., December 14, 2007; 282(50): 36642 - 36651.
[Abstract] [Full Text] [PDF]

Home page
 J. Appl. Physiol.Home page
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]

Home page
 J. Appl. Physiol.Home page
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]

Home page
 J. Appl. Physiol.Home page
C. C. Kuo, J. A. Fattor, G. C. Henderson, and G. A. Brooks
Lipid oxidation in fit young adults during postexercise recovery
J Appl Physiol, July 1, 2005; 99(1): 349 - 356.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
M. J. Roef, K. de Meer, S. C. Kalhan, H. Straver, R. Berger, and D.-J. Reijngoud
Gluconeogenesis in humans with induced hyperlactatemia during low-intensity exercise
Am J Physiol Endocrinol Metab, June 1, 2003; 284(6): E1162 - E1171.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
B. F. Miller, J. A. Fattor, K. A. Jacobs, M. A. Horning, S.-H. Suh, F. Navazio, and G. A. Brooks
Metabolic and cardiorespiratory responses to "the lactate clamp"
Am J Physiol Endocrinol Metab, November 1, 2002; 283(5): E889 - E898.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online