Effect of acute exercise on monocarboxylate transporters 1 and 4 in untrained and trained Thoroughbreds.

This study analyzes the short-term effects of high-intensity exercise on the expression of two proteins, monocarboxylate transporter 1 and 4, in the gluteus medius muscle of both untrained and trained horses. It was found that a single high-intensity exercise test resulted in temporary increases in the expression of these proteins, potentially shedding light on changes in lactate metabolism induced by exercise.

Research Methods

• The researchers conducted an incremental exercise test (IET) on a sample of 12 Thoroughbred horses, equally divided between males and females aged 3 to 4 years.
• The horses underwent two IETs, one prior to and one after 18 weeks of high-intensity exercise training (HIT).
• During the HIT period, the horses were exercised at 90% of their maximal oxygen consumption for 3 minutes during the first 10 weeks, and 110% of maximum oxygen consumption for 3 minutes during the final 8 weeks.
• Muscle biopsy samples were taken from the horses’ gluteus medius muscle before (baseline), immediately after, and then 3, 6, and 24 hours following the IET.

Research Findings

• The expression of monocarboxylate transporter 1 and 4 (MCT1 and MCT4) was increased 3 and 6 hours after the IET in muscle samples from untrained horses and 6 hours after the IET in muscle samples from trained horses.
• For both untrained and trained horses, there were increased amounts of MCT1 and MCT4 proteins 6 hours after the IET, but the levels were not different from baseline after 24 hours.
• The researchers concluded that the single IET resulted in temporary increases in MCT1 and MCT4 mRNA expression and protein content in both untrained and trained horses.

Implications

• The results of this study provide a platform for further research into the effects of exercise on lactate metabolism, as the proteins MCT1 and MCT4 are known to be involved in this process.
• Understanding the altered expression of these proteins in response to exercise could potentially enhance training and recovery strategies for high-performance horses in the future.