Effects of training on potassium homeostasis during exercise and skeletal muscle Na+,K(+)-ATPase concentration in young adult and middle-aged Dutch Warmblood horses.

The research explores the impact of short-term moderate exercise on potassium regulation in the plasma and erythrocytes, as well as the skeletal muscle sodium-potassium ATPase concentration in both young adult and middle-aged Dutch Warmblood horses.

Methodology

• The study involved four horses aged 4 to 6 years old, and another four aged 10 to 16 years old, all of Dutch Warmblood breed.
• Each horse underwent a 6-minute exercise test before and after a 12-day training period.
• Specimens from the gluteus medius and semitendinosus muscles were analyzed before and after the training period to measure the concentration of Sodium-Potassium ATPase.
• Blood samples were also collected before, immediately after, and at several intervals after the exercise trial to measure various hematological variables and the concentration of potassium in plasma and whole blood.

Findings

• After training, there was a 32% increase in the Sodium-Potassium ATPase concentration in the gluteus medius muscle of middle-aged horses, as opposed to the pre-training values. However, the increased concentration had no impact on hyperkalemia development during exercise.
• Despite the absence of any noticeable change in the Sodium-Potassium ATPase concentration in either muscle, the onset of hyperkalemia during exercise in young horses was slightly blunted, albeit not significantly.
• The concentration of potassium within the erythrocytes of both horse age groups was found to rise by 7% to 10% after training. However, the exercise trials did not influence this concentration variation.

Conclusions

• The findings suggest that as horses age, the activation of skeletal muscle Sodium-Potassium ATPase during exercise likely decreases.
• Training appears to boost the activity of Sodium-Potassium ATPase in skeletal muscles, resulting in an increased Sodium-Potassium ATPase concentration if the existing capacity of Sodium-Potassium ATPase cannot fulfill requirements.