Exercise training restores uncoupling protein-3 content in limb muscles of patients with chronic obstructive pulmonary disease

Am J Physiol Endocrinol Metab. 2006 May;290(5):E976-81. doi: 10.1152/ajpendo.00336.2005. Epub 2005 Dec 13.


Oxidative capacity and uncoupling protein-3 (UCP3) content are reduced in limb muscles of patients with chronic obstructive pulmonary disease (COPD). It has been hypothesized that the physiological role of UCP3 is to protect mitochondria against lipotoxicity in cases where fatty acid influx exceeds the capacity to oxidize them. Exercise training improves oxidative capacity and reduces UCP3 protein content in healthy subjects, but the response of UCP3 to training in COPD is unknown. We studied the effect of exercise training on UCP3 content in limb muscles of COPD patients. For this, seven healthy age-matched subjects and thirteen patients with COPD were studied. All patients were admitted to an 8-wk exercise training intervention. Exercise capacity was assessed by means of an incremental cycle ergometry test. Biopsies were taken from the vastus lateralis in which UCP3 and lipid peroxidation levels were determined by Western blotting. Citrate synthase and 3-hydroxyacyl-CoA dehydrogenase (HAD; an enzyme involved in fatty acid oxidation) were measured as indexes of muscle oxidative capacity. UCP3 in COPD was approximately 50% lower compared with healthy age-matched controls. In COPD, training induced upregulation of UCP3 [from 67.7 (SD 41.8) to 113.8 (SD 104.2) arbitrary units (AU), P = 0.062], especially in the patients who showed no increase in HAD activity [from 80.9 (SD 52.6) to 167.9 (SD 109.1) AU, P = 0.028], whereas lipid peroxidation levels remained unaltered. We conclude that exercise-training can restore muscle UCP3 protein level in COPD, and the nature of this response complies with the hypothesis that UCP3 may protect against lipotoxicity.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-Hydroxyacyl CoA Dehydrogenases / metabolism
  • Aged
  • Aldehydes / analysis
  • Aldehydes / metabolism
  • Carrier Proteins / metabolism*
  • Citrate (si)-Synthase / metabolism
  • Exercise / physiology*
  • Exercise Test
  • Female
  • Glycogen Phosphorylase / metabolism
  • Humans
  • Ion Channels
  • Male
  • Middle Aged
  • Mitochondrial Proteins
  • Myosin Heavy Chains / analysis
  • Phosphofructokinase-1 / metabolism
  • Protein Isoforms / analysis
  • Pulmonary Disease, Chronic Obstructive / metabolism*
  • Pulmonary Disease, Chronic Obstructive / physiopathology
  • Pulmonary Disease, Chronic Obstructive / therapy
  • Quadriceps Muscle / chemistry
  • Quadriceps Muscle / enzymology
  • Quadriceps Muscle / metabolism*
  • Uncoupling Protein 3
  • Up-Regulation


  • Aldehydes
  • Carrier Proteins
  • Ion Channels
  • Mitochondrial Proteins
  • Protein Isoforms
  • UCP3 protein, human
  • Uncoupling Protein 3
  • 3-Hydroxyacyl CoA Dehydrogenases
  • Citrate (si)-Synthase
  • Glycogen Phosphorylase
  • Phosphofructokinase-1
  • 1-phosphofructokinase
  • Myosin Heavy Chains
  • 4-hydroxy-2-nonenal