Exercise training and clenbuterol reduce insulin resistance of obese Zucker rats

C. E. Torgan, J. T. Brozinick, E. A. Banks, M. Y. Cortez, R. E. Wilcox, J. L. Ivy

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


This study compared the effects of aerobic exercise training and chronic administration of the selective β2-adrenergic agonist clenbuterol on whole body and skeletal muscle insulin resistance in obese (fa/fa) Zucker rats. Obese rats were randomly assigned to training, clenbuterol, or sedentary control groups. Lean littermates served as a second control group. After 4-5 wk of treatment, an oral glucose tolerance test was performed, followed 1 wk later by hindlimb perfusion, during which time the rates of glucose uptake and 3-O-methyl-D-glucose (3-MG) transport were assessed in the presence of a submaximal (500 μU/ml) insulin concentration. Training resulted in a significant increase in citrate synthase and cytochrome oxidase activity in the recruited muscles. Clenbuterol induced a large increase in muscle mass but provoked a significant decrease in oxidative enzyme activity and β- adrenergic receptor density. Both treatments increased glucose tolerance and reduced the postglucose insulin response, with the improvements being more pronounced in the clenbuterol group. However, only exercise training improved insulin-stimulated hindlimb muscle glucose uptake (11.37 ± 0.65, 8.73 ± 0.77, and 8.27 ± 0.41 μmol · g-1 · h-1 for trained, clenbuterol, and sedentary control groups, respectively) and 3-MG transport. These results suggest that aerobic exercise training attenuated the insulin-resistant condition in the obese Zucker rat by a mechanism other than or in addition to β2-adrenergic receptor activation.

Original languageEnglish (US)
Pages (from-to)E373-E379
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number3 27-3
StatePublished - 1993


  • fiber type
  • glucose tolerance
  • glucose transport
  • glucose uptake
  • oxidative enzymes
  • skeletal muscle

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)


Dive into the research topics of 'Exercise training and clenbuterol reduce insulin resistance of obese Zucker rats'. Together they form a unique fingerprint.

Cite this