Curtin N A, Clapham J C, Barclay C J
Biological Structure and Function Section, Division of Biomedical Sciences, Faculty of Medicine, Sir Alexander Fleming Building, Imperial College, London SW7 2AZ, UK.
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.
将过表达解偶联蛋白3（UCP - 3tg）的小鼠比目鱼肌肌纤维束的收缩和能量性能与野生型小鼠肌纤维束的性能进行了比较。在L(o)（产生力的最佳长度）下进行了一系列30次0.2秒的等长强直收缩，期间测量了力和热量产生。UCP - 3tg纤维与野生型纤维一样强壮，并且在该系列中同样良好地维持力；在第一次强直收缩中，力分别为116.9±15.1和133.3±19.7 mN×mm(-2)（所有值均为平均值±标准误，UCP - 3tg组n = 6，野生型组n = 5）。热量产生被分为初始热（由于收缩性ATP酶和肌酸激酶反应）和恢复热（由于其他ATP供应过程），并相对于第一个周期的总热量表示。UCP - 3tg纤维和野生型纤维的初始热产生相似，在该系列中从0.799±0.052相对单位降至0.661±0.061相对单位（UCP - 3tg）以及从0.
