Potassium and lactate uptake by noncontracting tissue during strenuous exercise.

This research shows that potassium and lactate, which increase in the bloodstream during high intensity exercise, are taken up by noncontracting tissues in the bodies of strenuously exercising horses. This helps to regulate the plasma concentrations of these ions in the horse’s body.

Study setup

• The researchers aimed to test their hypothesis that potassium and lactate ions, which efflux from active skeletal muscles during strenuous exercise, are taken up by noncontracting tissue in the bodies of horses undergoing strenuous exercise.
• They performed their study on Standardbred horses , making them perform strenuous treadmill exercise for 4.5 minutes.
• Blood samples were taken from the carotid artery (CA), femoral vein (FV), and transverse facial vein (TFV) of the horses, which allowed measurement of plasma potassium and lactate concentrations.
• The differences in these substances between the active and noncontracting tissues were also calculated.

Results

• After three minutes of strenuous exercise, the researchers found that the plasma potassium concentration in the FV blood was greater than in the CA blood, and both these concentrations were greater than that in the TFV blood.
• Similarly, the plasma lactate concentrations also increased in CA and FV bloods, and these concentrations were greater than that in the TFV blood.
• These results indicated that potassium and lactate are being taken up by noncontracting tissues as they were found in lesser concentrations in TFV blood, related to noncontracting tissue.
• The magnitude of difference for both potassium and lactate concentrations increased across active and noncontracting tissue during high-speed exercise, but the directions were opposite. This supports the conclusion of release by active tissue and uptake by noncontracting tissue.

Conclusion

• This study provided evidence for the original hypothesis, demonstrating that noncontracting tissues do indeed uptake potassium and lactate during the course of strenuous exercise.
• This finding explains how the body manages to regulate the concentrations of these ions in the plasma during heavy exercise, preventing a harmful build-up that could otherwise ensue.