Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8574, Japan.
Exp Physiol. 2011 Mar;96(3):348-55. doi: 10.1113/expphysiol.2010.055483. Epub 2010 Dec 10.
The aim of this study was to investigate the effects of training and detraining on the monocarboxylate transporter (MCT) 1 and MCT4 levels in the gluteus medius muscle of Thoroughbred horses. Twelve Thoroughbred horses were used for the analysis. For 18 weeks, all the horses underwent high-intensity training (HIT), with running at 90-110% maximal oxygen consumption (VO2 max ) for 3 min, 5 days week(-1). Thereafter, the horses either underwent detraining for 6 weeks by either 3 min of moderate-intensity training (MIT) at 70% VO2 max, 5 days week(-1) (HIT-MIT group) or stall rest (HIT-SR group). The horses underwent an incremental exercise test, VO2 max was measured and resting muscle samples were obtained from the middle gluteus muscle at 0, 18 and 24 weeks. The content of MCT1 and MCT4 proteins increased after 18 weeks of HIT. At the end of this period, an increase was noted in the citrate synthase activity, while phosphofructokinase activity remained unchanged. After 6 weeks of detraining, all these indexes returned to the pretraining levels in the HIT-SR group. However, in the HIT-MIT group, the increase in the MCT1 protein content and citrate synthase activity was maintained after 6 weeks of MIT, while the MCT4 protein content decreased to the pretraining value. These results suggest that the content of MCT1 and MCT4 proteins increases after HIT in Thoroughbred horses. In addition, the increase in the MCT1 protein content and oxidative capacity induced by HIT can be maintained by MIT of 70% VO2 max, but the increase in the MCT4 protein content cannot be maintained by MIT.
本研究旨在探讨训练和停训对纯种马臀中肌单羧酸转运蛋白（MCT）1 和 MCT4 水平的影响。分析中使用了 12 匹纯种马。18 周内，所有马匹均接受高强度训练（HIT），以 90-110%最大摄氧量（VO2 max）进行 3 分钟，每周 5 天。此后，马匹通过 70%VO2 max 的 3 分钟中度强度训练（MIT）（HIT-MIT 组）或马厩休息（HIT-SR 组）进行 6 周的停训。马匹进行递增运动测试，测量 VO2 max，并在 0、18 和 24 周时从臀中肌中部获得静息肌肉样本。HIT 18 周后，MCT1 和 MCT4 蛋白含量增加。在此期间结束时，柠檬酸合酶活性增加，而磷酸果糖激酶活性保持不变。停训 6 周后，HIT-SR 组的所有这些指标均恢复到训练前水平。然而，在 HIT-MIT 组中，MIT 6 周后 MCT1 蛋白含量和柠檬酸合酶活性的增加得以维持，而 MCT4 蛋白含量下降到训练前水平。这些结果表明，HIT 后纯种马的 MCT1 和 MCT4 蛋白含量增加。此外，HIT 引起的 MCT1 蛋白含量增加和氧化能力可以通过 70%VO2 max 的 MIT 维持，但 MCT4 蛋白含量的增加不能通过 MIT 维持。
