Composition of sweat of the horse during prolonged epinephrine (adrenaline) infusion, heat exposure, and exercise.

The research article reviews how different factors, such as epinephrine (adrenaline) infusion, heat exposure, and exercise, affect the sweat composition in horses and ponies. The findings show how these factors change the levels of different elements like sodium, potassium, chloride, calcium, magnesium, and others in the sweat.

Research Procedure

• The researchers studied temporal changes in sweat composition in four horses during various conditions. These include epinephrine infusion, heat exposure, and exercise.
• The epinephrine infusion was at a rate of 0.13 to 0.31 micrograms/kg/min for a 3-hour duration, while the heat exposure was at 41 degrees Celsius with a wet bulb temperature of 33 degrees Celsius, for 5 to 6 hours.
• The exercise involved was a run at a speed of 16 to 18 km/hr for a distance of 58 to 80 km.
• They also expanded this study to four ponies who were exposed to heat.

Findings

• The sweat produced in response to each of these stimuli contained high levels of electrolytes like sodium, potassium and chloride.
• These concentrations remained constant during the middle period of the experiments. They only changed at the start of and towards the end of the experiments.
• The sweat generated from adrenaline infusion had significantly more sodium and dramatically less potassium than the sweat produced due to heat exposure.
• Moreover, the ratio of sweat sodium to potassium varied among the three different stimuli.
• Calcium concentration decreased over time and was low after 15 minutes of adrenaline-induced sweating.
• In contrast, the concentrations of magnesium and protein decreased exponentially with time. Despite their high correlation, the magnesium was not protein-bound.
• Urea concentration in sweat was found to be directly related to plasma urea concentration.
• Additionally, a rise in plasma glucose concentration to over 10 to 12 mmole/L during adrenaline infusion led to the appearance of glucose in sweat. Its concentration in sweat rose to 8 to 12 mmole/L when plasma glucose was more than 20 mmole/L.