Role of glucose transport in glycogen supercompensation in reweighted rat skeletal muscle

Erik J. Henriksen, Craig S. Stump, Thanh Hang T. Trinh, Sean D. Beaty

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Hindlimb weight bearing after a 3-day period of hindlimb suspension (reweighting) of juvenile rats results in a marked transient elevation in soleus glycogen concentration that cannot be explained on the basis of the activities of glycogen synthase and phosphorylase. We have hypothesized that enhanced glucose transport activity could underlie this response. We directly tested this hypothesis by assessing the response of insulin-dependent and insulin-independent glucose transport activity (in vitro 2-[1,2-3H]deoxy-D- glucose uptake) as well as glucose transporter (GLUT-4) protein levels during a 48-h reweighting period. After a net glycogen loss (from 29 ± 2 to 16 ± 1 nmol/mg muscle; P < 0.05) during the first 2 h of reweighting, glycogen accumulated at an average rate of 1.4 nmol · mg-1 · h-1 up to 18 h, reaching an apex of 38 ± 1 nmol/mg. During this same reweighting period, insulin-independent, but not insulin-dependent, glucose transport activity was significantly enhanced (P < 0.05 vs. weight-bearing control values) and was associated with an elevated level of GLUT-4 protein and the specific activity of total hexokinase. The specific activity of citrate synthase was also increased. By 24 h of reweighting, although insulin-independent glucose transport activity and GLUT-4 protein remained elevated, glycogen accumulation had ceased, likely due to enhanced phosphorylase activity at this time point. These results are consistent with the interpretation that the glycogen supercompensation seen during reweighting of the rat soleus may be regulated in part by an enhanced glucose flux arising from an increase in insulin-independent glucose transport activity and hexokinase activity.

Original languageEnglish (US)
Pages (from-to)1540-1546
Number of pages7
JournalJournal of Applied Physiology
Volume80
Issue number5
DOIs
StatePublished - May 1996

Keywords

  • 2-[1,2-H]deoxy- D-glucose uptake
  • GLUT-4 protein
  • citrate synthase
  • hexokinase
  • simulated weightlessness
  • soleus muscle
  • weight bearing

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Fingerprint Dive into the research topics of 'Role of glucose transport in glycogen supercompensation in reweighted rat skeletal muscle'. Together they form a unique fingerprint.

  • Cite this