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Experimental physiology2021; 106(4); 972-982; doi: 10.1113/EP089232

Tracing oral Na+ and K+ in sweat during exercise and recovery in horses.

Abstract: What is the central question of this study? What are the mechanisms by which equine sweat glands transport sodium, potassium and water into sweat? What is the main finding and its importance? The flux of sodium into sweat does not have an active transport component, the flux of potassium into sweat is partially dependent on an active transport mechanism, and there is no evidence for paracellular transport. In two series of experiments, this study used radioactive sodium (Na ) and potassium (K ) to trace the net flux, and calculate the unidirectional fluxes, of these ions from extracellular fluid into sweat of horses during exercise and recovery. The effect of an oral electrolyte supplement (PNW) on the sweating responses and ion fluxes was also examined. Compared to 8 litres of water (controls), provision of 8 litres of PNW resulted in significantly increased sweating duration (P < 0.001). Two hours before exercise, Tc-labelled diethylene-triamine-pentaacetate (DTPA) was administered i.v. to determine if there was paracellular flux of this molecule in sweat glands during the period of sweating. One hour before beginning moderate-intensity exercise, horses were nasogastrically administered either Na (1-3 litres) or K (8 litres) with water (control) or an electrolyte supplement. Both radiotracers appeared in sweat within 10 min of exercise onset, and the sweat specific activity of both ions increased during exercise (P < 0.001), approaching plasma specific activities. There was no appearance of Tc-DTPA in sweat. The activities of Na and K, together with the concentrations Na , K and Cl , argued against significant paracellular flux of these ions into the lumen of sweat glands. The flux analysis for Na indicated a small intracellular pool within sweat gland cells, and no evidence for an active transport component. The flux analysis for K indicated a relatively large intracellular equilibration pool within sweat gland cells, with evidence for an active transport component. The results are discussed with respect to the current understanding of sweat gland epithelial cell ion transport mechanisms at both the basal and the apical membranes. It appears likely that the majority of ions appearing in sweat pass through sweat gland epithelial cells by transcellular mechanisms that include ion transporting pathways as well as apical vesicular exocytosis.
© 2021 The Authors. Experimental Physiology © 2021 The Physiological Society.
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Publication Date: 2021-02-16 PubMed ID: 33550621DOI: 10.1113/EP089232Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research study investigates how sweat glands transport sodium and potassium in horses during exercise and their recovery period. The primary findings suggest that sodium flux into sweat does not involve an active transport component, potassium flux partially depends on an active transport mechanism, and paracellular transport is not evident. The study also suggests that an oral electrolyte supplement extends the duration of sweating in horses.

Study Design and Protocol

The study conducted two sequences of experiments using radioactive sodium (Na) and potassium (K) to monitor and calculate the net and unidirectional transfers of these ions from the fluid surrounding cells to horse sweat. It also explored:

  • The impact of an oral electrolyte supplement (PNW) on the duration of sweating and ion transfers.
  • The potential paracellular flux involved in the sweat glands.

An hour before a moderated-intensity workout, the researchers provided horses with radioactive Na or K, along with either water or the electrolyte supplement. The observation that the radiotracers surfaced in the sweat within 10 minutes of exercise onset was a significant finding.

To determine any paracellular flux, they administered a radioactive molecule (Tc-DTPA) to the participating horses two hours before the workout.

Major Findings

The higher presence of radioactive Na and K in sweat during exercise indicated a probable absence of significant paracellular flux into the sweat glands. The results for Na demonstrated the existence of a small intracellular pool within the sweat gland cells and no evidence for an active transport component. On the other hand, the results for K revealed a relatively larger intracellular pool, with proof of an active transport element involved.

There was no appearance of Tc-DTPA in the sweat, further corroborating the absence of paracellular movement.

The researchers also observed that the electrolyte supplement PNW resulted in an increased sweating duration compared to plain water-serving as controls.

Interpretation and Implications

The findings suggest that the majority of ions appearing in sweat pass through sweat gland epithelial cells by transcellular mechanisms. These may include ion transporting pathways as well as apical vesicular exocytosis. There seems to be no significant involvement of paracellular transport in the ion movement, as per the absence of Tc-DTPA in the sweat.

From an exercise physiology perspective, the research implicates the active involvement of sweat gland epithelial cells in directing ion flux during exercise. The increased induction of sweat by the oral electrolyte supplement underscores potential benefits for sustaining hydration levels or thermo-regulation in performance horses.

Cite This Article

APA
Lindinger MI, Waller AP. (2021). Tracing oral Na+ and K+ in sweat during exercise and recovery in horses. Exp Physiol, 106(4), 972-982. https://doi.org/10.1113/EP089232

Publication

Experimental physiology
ISSN: 1469-445X
NlmUniqueID: 9002940
Country: England
Language: English
Volume: 106
Issue: 4
Pages: 972-982

Researcher Affiliations

Lindinger, Michael I
  • Research and Development, The Nutraceutical Alliance Inc., Burlington, Ontario, Canada.
Waller, Amanda P
  • Center for Clinical & Translational Research, Nationwide Children's Hospital, Columbus, OH, USA.

MeSH Terms

  • Animals
  • Chlorides / metabolism
  • Horses
  • Physical Conditioning, Animal / physiology
  • Potassium / metabolism
  • Sodium / metabolism
  • Sweat / metabolism
  • Sweating
  • Water

References

This article includes 33 references
  1. Dean RB, Noonan TR, Haege L, Fenn WO. Permeability of erythrocytes to radioactive Potassium. Journal of General Physiology 24, 353-365.
  2. D'Innocenzo B, Salzano AM, D'Ambrosio C, Gazzano A, Niccolini A, Sorce C, Dani FR, Scaloni A, Pelosi P. Secretory proteins as potential semiochemical carriers in the horse. Biochemistry 45, 13418-13428.
  3. Ecker GL, Lindinger MI. Effects of terrain, speed, temperature and distance on water and ion losses. Equine Veterinary Journal 27, 298-305.
  4. Eckersall PD, Beeley JG, Snow DH, Thomas A. Characterisation of glycoproteins in the sweat of the horse (Equus caballus). Research in Veterinary Science 36, 231-234.
  5. Evans CL, Smith DF. Sweating responses in the horse. Proceedings of Royal Society of London Series B, Biological Sciences 144, 61-83.
  6. Geor RJ, McCutcheon LJ, Ecker GL, Lindinger MI. Heat storage in horses during submaximal exercise before and after humid heat acclimation. Journal of Applied Physiology (1985) 89(6), 2283-2293.
  7. Gottlieb-Vedi M, Dahlborn K, Jansson A, Wroblewski R. Elemental composition of muscle at rest and potassium levels in muscle, plasma and sweat of horses exercising at 20°C and 35°C. Equine Veterinary Journal Supplement 28, 35-41.
  8. Hodgson DR. Thermoregulation. In D. R. Hodgson C. M., McGowan & K. H. McKeever (Eds.), The Athletic Horse: Principles and Practice of Equine Sports Medicine (2nd edn., pp. 108-124). Elsevier Inc..
  9. Hodgson DR, McCutcheon LJ, Byrd SK, Brown WS, Bayly WM, Brengelmann GL, Gollnick PD. Dissipation of metabolic heat in the horse during exercise. Journal of Applied Physiology (1985) 74(3), 1161-1170.
  10. Huang Y, Ko WH, Chung YW, Wong PYD. Identification of calcium-activated potassium channels in cultured equine sweat gland epithelial cells. Experimental Physiology 84, 881-895.
  11. Jenkinson DME, Elder HY, Bovell DL. Equine sweating and anhidrosis part 1 - Equine sweating. Veterinary Dermatology 17, 361-392.
  12. Jenkinson DME, Nimmo MC, Jackson D, McQueen L, Elder HY, Mackay DA, Montgomery I. Comparative studies of the effect of thermal stimulation on the permeability of the luminal cell junctions of the sweat gland to lanthanum. Tissue & Cell 15, 573-581.
  13. Kirschner LB. The study of NaCl transport in aquatic animals. Integrative and Comparative Biology 10, 365-376.
  14. Ko WH, Chan HC, Cheng Chew SB, Wong PYD. Ionic mechanisms of Ca2+-dependent electrolyte transport across equine sweat gland epithelium. Journal of Physiology 493, 885-894.
  15. Ko WH, Chan HC, Wong PYD. Anion secretion induced by capacitative Ca2+ entry through apical and basolateral membranes of cultured equine sweat gland epithelium. Journal of Physiology 497, 19-29.
  16. Ko WH, Law VWY, Wong HY, Wilson SM. The simultaneous measurement of epithelial ion transport and intracellular free Ca2+ in cultured equine sweat gland secretory epithelium. Journal of Membrane Biology 170, 205-211.
  17. Lindinger MI, Ecker GL. Gastric emptying, intestinal absorption of electrolytes and exercise performance in electrolyte-supplemented horses. Experimental Physiology 98, 193-206.
  18. Lindinger MI, Heigenhauser GJ. Intracellular ion content of skeletal muscle measured by instrumental neutron activation analysis. Journal of Applied Physiology 63, 426-433.
  19. McCutcheon LJ, Geor RJ. Influence of training on sweating responses during submaximal exercise in horses. Journal of Applied Physiology 89, 2463-2471.
  20. McCutcheon LJ, Geor RJ, Ecker GL, Lindinger MI. Equine sweating responses to submaximal exercise during 21 days of heat acclimation. Journal of Applied Physiology 87, 1843-1851.
  21. McCutcheon LJ, Geor RJ, Hare MJ, Ecker GL, Lindinger MI. Sweating rate and sweat composition during exercise and recovery in ambient heat and humidity. Equine Veterinary Journal 27, 153-157.
  22. Minty BD, Royston D, Jones JG, Smith DJ, Searing CS, Beeley M. Changes in permeability of the alveolarcapillary barrier in firefighters. British Journal of Industrial Medicine 42(9), 631-634.
  23. Montgomery I, McEwan Jenkinson D, Elder HY. The effects of thermal stimulation on the ultrastructure of the fundus and duct of the equine sweat gland. Journal of Anatomy 135, 13-28.
  24. Robertson J. Theory and use of tracers in determining rates in biological systems. Physiological Reviews 37, 133-154.
  25. Rose RJ, Arnold KS, Church S, Paris R. Plasma and sweat electrolyte concentrations in the horse during long distance exercise. Equine Veterinary Journal 12, 19-22.
  26. Snow DH, Kerr MG, Nimmo MA, Abbott EM. Alterations in blood, sweat, urine and muscle composition during prolonged exercise in the horse. Veterinary Record 110, 377-384.
  27. Sorenson V, Prasad G. On the fine structure of horse sweat glands. Zeitschrift für Anatomie und Entwicklungsgeschichte 139, 173-183.
  28. Sullivan LP, Wallace DP, Grantham JJ. Epithelial transport in polycystic kidney disease. Physiological Reviews 78, 1165-1191.
  29. Takagi S, Tagawa M. A cytological and cytochemical study of the sweat gland of the horse. Japanese Journal of Physiology 9, 153-159.
  30. Waller A, Lindinger MI. Time course and magnitude of fluid and electrolyte shifts during recovery from high-intensity exercise in Standardbred racehorses. Equine and Comparative Exercise Physiology 2, 77-87.
  31. Wilson SM, Elder HY, McEwan Jenkinson D, McWilliams SA. The effects of thermally induced activity in vivo upon the levels of sodium, chlorine and potassium in the epithelia of the equine sweat gland. Journal of Experimental Biology 136, 489-494.
  32. Wilson SM, Ko WH, Pediani JD, Rakhit S, Nichol JA, Bovell DL. Calcium-dependent regulation of membrane ion permeability in a cell line derived from the equine sweat gland epithelium. Comparative Biochemistry & Physiology Part A: Physiology 111, 215-221.
  33. Wilson SM, Pediani JD, Ko WH, Bovell DL, Kitson S, Montgomery I, Brown UM, Smith GL, Elder HY, Jenkinson DM. Investigation of stimulus-secretion coupling in equine sweat gland epithelia using cell culture techniques. Journal of Experimental Biology 183, 279-299.

Citations

This article has been cited 4 times.
  1. Waller AP, Lindinger MI. Tracing Acid-Base Variables in Exercising Horses: Effects of Pre-Loading Oral Electrolytes. Animals (Basel) 2022 Dec 24;13(1).
    doi: 10.3390/ani13010073pubmed: 36611683google scholar: lookup
  2. Lindinger MI. Oral Electrolyte and Water Supplementation in Horses. Vet Sci 2022 Nov 10;9(11).
    doi: 10.3390/vetsci9110626pubmed: 36356103google scholar: lookup
  3. Abraham AJ, Duvall ES, Doughty CE, Riond B, Ortmann S, Terranova M, le Roux E, Clauss M. Sodium Retention in Large Herbivores: Physiological Insights and Zoogeochemical Consequences. J Exp Zool A Ecol Integr Physiol 2025 Jul;343(6):664-676.
    doi: 10.1002/jez.2924pubmed: 40247661google scholar: lookup
  4. Maier I, Kienzle E. A Meta-Analysis on Quantitative Sodium, Potassium and Chloride Metabolism in Horses and Ponies. Animals (Basel) 2025 Jan 13;15(2).
    doi: 10.3390/ani15020191pubmed: 39858191google scholar: lookup
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