Sweat production and localisation of carbonic anhydrase in the equine sweat gland during exercise at two ambient temperatures.

The research investigates sweat production in horses during exercise in different temperature settings and focuses on the role of the enzyme carbonic anhydrase within the sweat glands.

Research Objectives

• The primary objective of the research was to examine the production of sweat when the horses were subjected to exercise in two different temperature conditions: 20 degrees C and 35 degrees C.
• Concurrently, the researchers wished to determine the location and activity of the enzyme carbonic anhydrase (CA) in the sweat gland, an enzyme known to catalyze the reaction between Carbon Dioxide (CO2) and water (H2O), creating bicarbonate (HCO3-) and a hydrogen ion (H+).
• The interest in CA comes from the understanding that horses develop alkalosis when they engage in prolonged exercise and their sweat contains bicarbonate (HCO3-). Alkalosis refers to when your body has too many bases due to the loss of acids, leading to higher pH levels in the blood.

Methodology and Findings

• Four standardbred trotting horses took part in the exercise tests. Skin biopsies were acquired from the horses’ necks, and sweat rate, skin temperature, and blood temperature were measured continuously.
• The study found a strong correlation between the sweat rate, temperature, and the intensity of the work done by the horse at 20 degrees C. But at 35 degrees C, both the temperature and sweat rate were higher, remaining elevated despite a reduction in the horse’s exercise intensity.
• The researchers observed that after exercise at 35 degrees C, there was a significant decrease in the sweat gland cell area that corresponded with a reduction in vesicles—the small structures within a cell that carry out specific functions.
• Strong carbonic anhydrase activity was detected on the luminal (inner surface) cell membrane, with weaker activity basolaterally (at the base). Moreover, the intensity of the enzyme’s staining increased after the horse had exercised, indicating higher enzyme activity.

Conclusion

• The study suggests that carbonic anhydrase could play a crucial role in regulating the alkaline conditions developed in the body after exercise. This is done by providing bicarbonate ions (HCO3-) to counteract the alkaline pH levels in sweat, effectively combatting alkalosis.