Effect of training and detraining on monocarboxylate transporter (MCT) 1 and MCT4 in Thoroughbred horses

Abstract

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 (V O 2 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%V O 2 max , 5 days week −1 (HIT-MIT group) or stall rest (HIT-SR group). The horses underwent an incremental exercise test,V O 2 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%V O 2 max , but the increase in the MCT4 protein content cannot be maintained by MIT.

Expression of monocarboxylate transporter (MCT) 1 and MCT4 in overloaded mice plantaris muscle

“…Previous studies showed that MCT1 is increased by the most type of training, while sprint and strength training can up-regulate MCT4 expression [12]. Interestingly, we have previously found that increased MCT4 by high-intensity training could not be maintained by moderate-intensity training in horses [21]. However, it remains a challenge to understand the mechanisms determining which factor affects the expression of MCTs.…”

Sequence variations and two levels of MCT1 and CD147 expression in red blood cells and gluteus muscle of horses

“…Likewise, the physiological importance of the phenomenon is unclear. It has been shown that the amount of MCTs in muscle has been increased by training in horses (Kitaoka et al, 2011) and thus it is important for physiological capacity. It can be speculated, however, that LTA in RBC must also be beneficial, because it has surveyed evolution and breeding.…”

Nothing ‘evil’ and no ‘conundrum’ about muscle lactate production

“…This is where the previous research on monocarbolylate transporters becomes more interesting (Juel, 1997), to which the data of Kitaoka et al (2011) form the most recent contribution. The increased density of monocarboxylate transport proteins 1 and 4 (MCT1 and MCT4) after intense exercise training in the horse (Kitaoka et al 2011) is logical to the need to sustain muscle lactate production during intense exercise. The rapid and high capacity for lactate removal is essential to minimize muscle lactate accumulation or, alternatively, to prolong the time and increase the metabolic flux to attain a given muscle lactate accumulation.…”