Effects of exercise training and antioxidant R-ALA on glucose transport in insulin-sensitive rat skeletal muscle

Vitoon Saengsirisuwan, Felipe R. Perez, Tyson R. Kinnick, Erik J. Henriksen

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

We have recently demonstrated (Saengsirisuwan V, Kinnick TR, Schmit MB, and Henriksen EJ, J Appl Physiol 91: 145-153, 2001) that exercise training (ET) and the antioxidant R-(+)-α-lipoic acid (R-ALA) interact in an additive fashion to improve insulin action in insulin-resistant obese Zucker (fa/fa) rats. The purpose of the present study was to assess the interactions of ET and R-ALA on insulin action and oxidative stress in a model of normal insulin sensitivity, the lean Zucker (fa/-) rat. For 6 wk, animals either remained sedentary, received R-ALA (30 mg·kg body wt-1·day-1), performed ET (tread- mill running), or underwent both R-ALA treatment and ET. ET alone or in combination with R-ALA significantly increased (P < 0.05) peak oxygen consumption (28-31%) and maximum run time (52-63%). During an oral glucose tolerance test, ET alone or in combination with R-ALA resulted in a significant lowering of the glucose response (17-36%) at 15 min relative to R-ALA alone and of the insulin response (19-36%) at 15 min compared with sedentary controls. Insulin-mediated glucose transport activity was increased by ET alone in isolated epitrochlearis (30%) and soleus (50%) muscles, and this was associated with increased GLUT-4 protein levels. Insulin action was not improved by R-ALA alone, and ET-associated improvements in these variables were not further enhanced with combined ET and R-ALA. Although ET and R-ALA caused reductions in soleus protein carbonyls (an index of oxidative stress), these alterations were not significantly correlated with insulin-mediated soleus glucose transport. These results indicate that the beneficial interactive effects of ET and R-ALA on skeletal muscle insulin action observed previously in insulin-resistant obese Zucker rats are not apparent in insulin-sensitive lean Zucker rats.

Original languageEnglish (US)
Pages (from-to)50-58
Number of pages9
JournalJournal of Applied Physiology
Volume92
Issue number1
DOIs
StatePublished - Jan 1 2002

Keywords

  • GLUT-4 protein
  • Glucose tolerance
  • Oxidative stress
  • Protein carbonyls
  • R-(+)-α-lipoic acid

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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