Effects of acute exercise and long-term exercise on total Na+,K+ -ATPase content and Na+,K+ -ATPase isoform expression profile in equine muscle.

This research assesses how both a single bout of exercise and long-term training affect the content and isoform expression of an important enzyme, Na(+),K(+)-ATPase, in horse muscle. It emphasizes the significance of studying these changes for better understanding certain neuromuscular conditions.

Methodology

• The study involved six Standardbred horses.
• Each horse underwent an exercise session on a treadmill before and after an 18-week combined interval and endurance training regimen.
• Muscle biopsy samples were taken from two specific muscles – the vastus lateralis muscle (VLM) and pectoralis descendens muscle (PDM), both before and after exercise.
• The researchers assessed the Na(+),K(+)-ATPase content, mRNA isoforms, and protein concentrations. They used [(3)H]ouabain binding, a real-time PCR assay, and western blotting techniques for this analysis.

Findings

• All six Na(+),K(+)-ATPase mRNA isoforms were found in horse muscle, but proteins were only detected from A2 and B1 isoforms.
• Exercise prior to the training program led to increased mRNA isoforms A1, A2, A3, and B2 in VLM, and A1 and B3 in PDM.
• The training regimen heightened resting values for mRNA isoforms A3 and B1 in VLM and B3 in PDM.
• Protein levels from mRNA A2 and B1, Na(+),K(+)-ATPase content, and [(3)H]ouabain binding all showed increase in VLM due to the training action. In the PDM, only the A2 protein increased because of the training.
• After the training process, the effects of a strenuous exercise session on mRNA expression were no longer noticeable.

Conclusions

• The equine muscle contained all Na(+),K(+)-ATPase mRNA isoforms, but only proteins from A2 and B1 isoforms got detected.
• Expressions of these isoforms showed changes due to the impact of strenuous exercise sessions and the long-term training corporate program. This illustrates an adaptive response of the muscle.
• The assessment of Na(+),K(+)-ATPase gene expression can indeed contribute effectively to understand changes in neuromuscular diseases related to muscle excitability.