Effect of soleus unweighting on stimulation of insulin-independent glucose transport activity

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16 Scopus citations

Abstract

Unweighting of the rat soleus by tail-cast suspension results in increased insulin action on stimulation of glucose transport, which can be explained, at least in part, by increased insulin binding and enhanced glucose transporter protein levels. Glucose transport is also activated by an insulin-independent mechanism stimulated by in vitro muscle contractions or hypoxia. Therefore, the purpose of this study was to determine if soleus unweighting leads to an enhanced response of the insulin-independent pathway for stimulation of glucose transport. The hindlimbs of juvenile male Wistar rats were suspended by a tail-cast system for 3 or 6 days. Glucose transport activity in isolated soleus strips (~18 mg) was then assessed by using 2- deoxy-[1,2-3H]glucose (2-DG) uptake. Insulin (2 mU/ml) had a progressively enhanced effect on 2-DG uptake after 3 and 6 days of unweighting (+44 and +72% vs. control, respectively; both P < 0.001). At these same times, there was no difference between groups for activation of 2-DG uptake by maximally effective treatments with contractions (10 tetanuses), hypoxia (60 min), or caffeine (5 mM). These results indicate that the enhanced capacity for stimulation of glucose transport after soleus unweighting is restricted to the insulin pathway, with no apparent enhancement of the insulin-independent pathway.

Original languageEnglish (US)
Pages (from-to)1653-1657
Number of pages5
JournalJournal of Applied Physiology
Volume74
Issue number4
DOIs
StatePublished - 1993

Keywords

  • 2-deoxy-[1,2-H]glucose uptake
  • caffeine
  • hypoxia
  • insulin
  • simulated weightlessness
  • skeletal muscle

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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