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Muscle K+, Na+, Cl- disturbances and Na+, K+- pump inactivation: implications for fatigue

McKenna, Michael J and Bangsbo, Jens and Renaud, Jean-Marc (2008) Muscle K+, Na+, Cl- disturbances and Na+, K+- pump inactivation: implications for fatigue. Journal of Applied Physiology, 104 (1). pp. 288-295. ISSN 0021-8987

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Abstract

Membrane excitability is a critical regulatory step in skeletal muscle contraction and is modulated by local ionic concentrations, conductances, ion transporter activities, temperature, and humoral factors. Intense fatiguing contractions induce cellular K efflux and Na and Cl influx, causing pronounced perturbations in extracellular (interstitial) and intracellular K and Na concentrations. Muscle interstitial K concentration may increase 1- to 2-fold to 11–13 mM and intracellular K concentration fall by 1.3- to 1.7-fold; interstitial Na concentration may decline by 10 mM and intracellular Na concentration rise by 1.5- to 2.0-fold. Muscle Cl concentration changes reported with muscle contractions are less consistent, with reports of both unchanged and increased intracellular Cl concentrations, depending on contraction type and the muscles studied. When considered together, these ionic changes depolarize sarcolemmal and t-tubular membranes to depress tetanic force and are thus likely to contribute to fatigue. Interestingly, less severe local ionic changes can also augment subtetanic force, suggesting that they may potentiate muscle contractility early in exercise. Increased Na-K-ATPase activity during exercise stabilizes Na and K concentration gradients and membrane excitability and thus protects against fatigue. However, during intense contraction some Na-K pumps are inactivated and together with further ionic disturbances, likely precipitate muscle fatigue.

Item Type: Article
Uncontrolled Keywords: ResPubID16108, potassium, sodium, Na+, - K+ - ATPase, exercise excitability
Subjects: Faculty/School/Research Centre/Department > Centre for Ageing, Rehabilitation, Exercise & Sport Science (CARES)
FOR Classification > 1116 Medical Physiology
SEO Classification > 970111 Expanding Knowledge in the Medical and Health Sciences
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Depositing User: VUIR
Date Deposited: 11 Sep 2011 23:32
Last Modified: 12 Sep 2011 01:31
URI: http://vuir.vu.edu.au/id/eprint/3831
DOI: 10.1152/japplphysiol.01037.2007
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Citations in Scopus: 61 - View on Scopus

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