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Home / Equine Research Bank / Exp Physiol / Tracing oral Na+ and K+ in sweat during exercise and recover...
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

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Citations

This article has been cited 2 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
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