Schrauwen P, Troost F J, Xia J, Ravussin E, Saris W H
Department of Human Biology, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.
Int J Obes Relat Metab Disord. 1999 Sep;23(9):966-72. doi: 10.1038/sj.ijo.0801026.
The new uncoupling proteins, UCP2 and UCP3, are thought to play a role in energy efficiency in humans. Endurance training has been suggested to have effects on resting metabolic rate and energy efficiency. We therefore determined UCP2 and UCP3 mRNA levels in skeletal muscle of trained and untrained male subjects.
Using reverse transcription-polymerase chain reaction (RT-PCR), expression of UCP2, UCP3L and UCP3S mRNA were measured in muscle biopsies from the quadriceps femoris in eight trained (23.9+/-1.6 y; 70.6+/-3.1 kg; 14+/-3% body fat; maximal power output (Wmax): 5. 6+/-0.4 W/kg; mean+/-s.d.) and 10 lean, untrained (22.1+/-2.9 y; 72. 0+/-7.9 kg; 18+/-4% body fat; Wmax: 3.9+/-0.4 W/kg; mean+/-s.d.) subjects. In six of the trained subjects, UCP2 and UCP3 mRNA were measured before and after an exercise bout to exhaustion. To correct for differences in mitochondrial content, levels of UCP2 and UCP3 mRNA were expressed relative to cytochrome-b, a marker of mitochondrial content.
Acute exercise had no effect on the expression of UCP3L or UCP3S, but in five out of six subjects UCP2 expression decreased after exercise, although the difference was not statistically significant (P=0.11). Trained subjects had significantly reduced mRNA levels of UCP3L (P=0.028) and UCP3S (P=0. 031). VO2max expressed per kg of fat-free mass was negatively correlated with UCP3L (r=-0.61, P=0.009) and UCP3S (r=-0.52, P=0. 028). Mechanical efficiency correlated negatively with UCP3L (r=-0. 56, P=0.019), UCP3S (r=-0.47, P=0.048) and tended to correlate with UCP2 (r=-0.46, P=0.06).
The lower levels of UCP3 mRNA in trained subjects and the inverse relationship of UCP3 expression and mechanical efficiency suggest that exercise training produces an adaptive physiological response in skeletal muscle improving mechanical efficiency.
新型解偶联蛋白UCP2和UCP3被认为在人类能量效率方面发挥作用。有人提出耐力训练会对静息代谢率和能量效率产生影响。因此，我们测定了受过训练和未受过训练的男性受试者骨骼肌中UCP2和UCP3的mRNA水平。
使用逆转录聚合酶链反应（RT-PCR），测量了8名受过训练的受试者（23.9±1.6岁；70.6±3.1千克；体脂14±3%；最大功率输出（Wmax）：5.6±0.4瓦/千克；平均值±标准差）和10名瘦的、未受过训练的受试者（22.1±2.9岁；72.0±7.9千克；体脂18±4%；Wmax：3.9±0.4瓦/千克；平均值±标准差）股四头肌肌肉活检样本中UCP2、UCP3L和UCP3S的mRNA表达。在6名受过训练的受试者中，在一次运动至疲劳前后测量了UCP2和UCP3的mRNA。为校正线粒体含量的差异，UCP2和UCP3的mRNA水平相对于细胞色素b（线粒体含量的标志物）进行表达。
急性运动对UCP3L或UCP3S的表达没有影响，但在6名受试者中的5名中，运动后UCP2表达下降，尽管差异无统计学意义（P = 0.11）。受过训练的受试者UCP3L（P = 0.028）和UCP3S（P = 0.031）的mRNA水平显著降低。每千克去脂体重的最大摄氧量（VO2max）与UCP3L（r = -0.61，P = 0.009）和UCP3S（r = -0.52，P = 0.028）呈负相关。机械效率与UCP3L（r = -0.56，P = 0.019）、UCP3S（r = -0.47，P = 0.048）呈负相关，并且与UCP2有负相关趋势（r = -0.46，P = 0.06）。
受过训练的受试者中UCP3 mRNA水平较低以及UCP3表达与机械效率的负相关关系表明，运动训练在骨骼肌中产生适应性生理反应，提高了机械效率。
