The role of sweat in maintaining the stimulation of effort homeostasis in horses.

Sweat secretion was analyzed quantitatively and qualitatively in 20 horses after a 5 min. gallop at 450 m/min. The analysis revealed concentration of proteins 63.3 +/- 6.47 g/l, mainly albumins, a high level of sodium 254.43 +/- 62.84 mM/,l chloride 268.68 +/- 98.46 mM/l, potassium 98.95 +/- 49.62 mM/l and calcium 4.14 +/- 0.8 mM/l. A dependence was found between the protein concentration in serum and its quantity in sweat and between the level of potassium in sweat and its loss from the cells within a range 8.6 to 25.8 mM/l. The hypertonic horse sweat protects organism for excessive water loss, the loss taking place by imperceptible evaporation. The loss of body weight amounted to 5.64 +/- 2.36 kg and the loss with the sweat was only 1.56 kg. Besides its thermoregulation function, the sweat ensures a proper effort homeostasis-isoosmic and isoionic status.