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Alkalosis increases muscle K+ release, but lowers plasma [K+] and delays fatigue during dynamic forearm exercise

Sostaric, Simon M., Skinner, Sandford L., Brown, Malcolm J., Sangkabutra, Termboon, Medved, Ivan, Medley, Tanya, Selig, Steve E., Fairweather, Ian, Rutar, Danny and McKenna, Michael J. 2006, Alkalosis increases muscle K+ release, but lowers plasma [K+] and delays fatigue during dynamic forearm exercise, Journal of physiology, vol. 570, no. 1, pp. 185-205, doi: 10.1113/jphysiol.2005.094615.

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Title Alkalosis increases muscle K+ release, but lowers plasma [K+] and delays fatigue during dynamic forearm exercise
Formatted title Alkalosis increases muscle K+ release, but lowers plasma [K+] and delays fatigue during dynamic forearm exercise
Author(s) Sostaric, Simon M.
Skinner, Sandford L.
Brown, Malcolm J.
Sangkabutra, Termboon
Medved, Ivan
Medley, Tanya
Selig, Steve E.ORCID iD for Selig, Steve E. orcid.org/0000-0003-4159-5111
Fairweather, Ian
Rutar, Danny
McKenna, Michael J.
Journal name Journal of physiology
Volume number 570
Issue number 1
Start page 185
End page 205
Publisher Wiley-Blackwell
Place of publication London, England
Publication date 2006-01
ISSN 0022-3751
1469-7793
Summary Alkalosis enhances human exercise performance, and reduces K+ loss in contracting rat muscle. We investigated alkalosis effects on K+ regulation, ionic regulation and fatigue during intense exercise in nine untrained volunteers. Concentric finger flexions were conducted at 75% peak work rate (-3 W) until fatigue, under alkalosis (Alk, NaHCO3, 0.3 g kg−1) and control (Con, CaCO3) conditions, 1 month apart in a randomised, double-blind, crossover design. Deep antecubital venous (v) and radial arterial (a) blood was drawn at rest, during exercise and recovery, to determine arterio-venous differences for electrolytes, fluid shifts, acid–base and gas exchange. Finger flexion exercise barely perturbed arterial plasma ions and acid–base status, but induced marked arterio-venous changes. Alk elevated [HCO3] and PCO2, and lowered [H+] (P < 0.05). Time to fatigue increased substantially during Alk (25 ± 8%, P < 0.05), whilst both [K+]a and [K+]v were reduced (P < 0.01) and [K+]a-v during exercise tended to be greater (P= 0.056, n= 8). Muscle K+ efflux at fatigue was greater in Alk (21.2 ± 7.6 µmol min−1, 32 ± 7%, P < 0.05, n= 6), but peak K+ uptake rate was elevated during recovery (15 ± 7%, P < 0.05) suggesting increased muscle Na+,K+-ATPase activity. Alk induced greater [Na+]a, [Cl]v, muscle Cl influx and muscle lactate concentration ([Lac]) efflux during exercise and recovery (P < 0.05). The lower circulating [K+] and greater muscle K+ uptake, Na+ delivery and Cl uptake with Alk, are all consistent with preservation of membrane excitability during exercise. This suggests that lesser exercise-induced membrane depolarization may be an important mechanism underlying enhanced exercise performance with Alk. Thus Alk was associated with improved regulation of K+, Na+, Cl and Lac.
Language eng
DOI 10.1113/jphysiol.2005.094615
Field of Research 119999 Medical and Health Sciences not elsewhere classified
Socio Economic Objective 970111 Expanding Knowledge in the Medical and Health Sciences
HERDC Research category C1.1 Refereed article in a scholarly journal
Copyright notice ©2006, The Authors
Persistent URL http://hdl.handle.net/10536/DRO/DU:30033445

Document type: Journal Article
Collection: School of Exercise and Nutrition Sciences
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