Excess recovery heat production by isolated muscles from mice overexpressing uncoupling protein-3

J Physiol. 2002 Jul 1;542(Pt 1):231-5. doi: 10.1113/jphysiol.2002.021964.


Contractile and energetic performance of bundles of muscle fibres from the soleus of mice overexpressing uncoupling protein 3 (UCP-3tg) were compared with the performance of bundles from wild-type mice. Force and heat production were measured during a series of thirty 0.2 s isometric tetani at L(o), the length optimal for force. UCP-3tg fibres were as strong as the wild-type and maintained force in the series equally well; in the first tetanus force was 116.9 +/- 15.1 and 133.3 +/- 19.7 mN x mm(-2) respectively (all values means +/- S.E.M., n = 6 for UCP-3tg and n = 5 for wild-type). Heat production was partitioned into initial heat (due to contractile ATPases and the creatine kinase reaction) and recovery heat (due to other ATP-supplying processes) and expressed relative to the first cycle total heat. Initial heat production was similar for the UCP-3tg and wild-type fibres, decreasing during the series from 0.799 +/- 0.052 to 0.661 +/- 0.061 relative units (UCP-3tg), and from 0.806 +/- 0.024 to 0.729 +/- 0.039 relative units (wild-type). In both types the recovery heat was small at the start of the series and increased as the series progressed. At the end of the series, recovery heat production by UCP-3tg fibres, 1.575 +/- 0.246 relative units, was twice that of the wild-type fibres, 0.729 +/- 0.072 relative units. The extra recovery heat represents inefficient recovery in UCP-3tg fibres. This is the first direct evidence of enhanced energy dissipation as heat when UCP-3tg is overexpressed.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Carrier Proteins / biosynthesis
  • Carrier Proteins / physiology*
  • Hot Temperature
  • Humans
  • In Vitro Techniques
  • Ion Channels
  • Isometric Contraction / physiology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Mitochondrial Proteins
  • Muscle, Skeletal / physiology*
  • Uncoupling Protein 3


  • Carrier Proteins
  • Ion Channels
  • Mitochondrial Proteins
  • UCP3 protein, human
  • Ucp3 protein, mouse
  • Uncoupling Protein 3
  • Adenosine Triphosphate