Relationships between electrolyte and amino acid compositions in sweat during exercise suggest a role for amino acids and K+ in reabsorption of Na+ and Cl- from sweat

Autoři: Grace R. Murphy aff001;  R. Hugh Dunstan aff001;  Margaret M. Macdonald aff001;  Nattai Borges aff001;  Zoe Radford aff001;  Diane L. Sparkes aff001;  Benjamin J. Dascombe aff001;  Timothy K. Roberts aff001
Působiště autorů: University of Newcastle, Callaghan, NSW, Australia aff001
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article
doi: 10.1371/journal.pone.0223381


Concentrations of free amino acids and [K+] in human sweat can be many times higher than in plasma. Conversely, [Na+] and [Cl-] in sweat are hypotonic to plasma. It was hypothesised that the amino acids and K+ were directly or indirectly associated with the resorption of Na+ and Cl- in the sweat duct. The implication would be that, as resources of these components became limiting during prolonged exercise then the capacity to resorb [Na+] and [Cl-] would diminish, resulting in progressively higher levels in sweat. If this were the case, then [Na+] and [Cl-] in sweat would have inverse relationships with [K+] and the amino acids during exercise. Forearm sweat was collected from 11 recreational athletes at regular intervals during a prolonged period of cycling exercise after 15, 25, 35, 45, 55 and 65 minutes. The subjects also provided passive sweat samples via 15 minutes of thermal stimulation. The sweat samples were analysed for concentrations of amino acids, Na+, Cl-, K+, Mg2+ and Ca2+. The exercise sweat had a total amino acid concentration of 6.4 ± 1.2mM after 15 minutes which was lower than the passive sweat concentration at 11.6 ± 0.8mM (p<0.05) and showed an altered array of electrolytes, indicating that exercise stimulated a change in sweat composition. During the exercise period, [Na+] in sweat increased from 23.3 ± 3.0mM to 34.6 ± 2.4mM (p<0.01) over 65 minutes whilst the total concentrations of amino acids in sweat decreased from 6.4 ± 1.2mM to 3.6 ± 0.5mM. [Na+] showed significant negative correlations with the concentrations of total amino acids (r = -0.97, p<0.05), K+ (r = -0.93, p<0.05) and Ca2+ (r = -0.83, p<0.05) in sweat. The results supported the hypothesis that amino acids and K+, as well as Ca2+, were associated with resorption of Na+ and Cl-.

Klíčová slova:

Amino acid analysis – Blood plasma – Body fluids – Electrolytes – Serine – Sweat – Sweat glands – Alanine


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