Fatigue depresses maximal in vitro skeletal muscle Na+-K+-ATPase activity in untrained and trained individuals

Fraser, Steve F., Jia, L. Li, Carey, Michael F., Wang, Xiao N., Sangkabutra, Termboon, Sostaric, Simon, Selig, Steve E., Kjeldsen, Keld and McKenna, Michael J. 2002, Fatigue depresses maximal in vitro skeletal muscle Na+-K+-ATPase activity in untrained and trained individuals, Journal of applied physiology, vol. 93, no. 5, pp. 1650-1659.

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Title Fatigue depresses maximal in vitro skeletal muscle Na+-K+-ATPase activity in untrained and trained individuals
Author(s) Fraser, Steve F.ORCID iD for Fraser, Steve F. orcid.org/0000-0003-0202-9619
Jia, L. Li
Carey, Michael F.
Wang, Xiao N.
Sangkabutra, Termboon
Sostaric, Simon
Selig, Steve E.ORCID iD for Selig, Steve E. orcid.org/0000-0003-4159-5111
Kjeldsen, Keld
McKenna, Michael J.
Journal name Journal of applied physiology
Volume number 93
Issue number 5
Start page 1650
End page 1659
Publisher American Physiological Society
Place of publication [Bethesda, Md.]
Publication date 2002-11-01
ISSN 8750-7587
Keyword(s) 3-O-methylfluoroscein phosphatase
Na+-K+ pump
Summary This study investigated whether fatiguing dynamic exercise depresses maximal in vitro Na+-K+-ATPase activity and whether any depression is attenuated with chronic training. Eight untrained (UT), eight resistance-trained (RT), and eight endurance-trained (ET) subjects performed a quadriceps fatigue test, comprising 50 maximal isokinetic contractions (180°/s, 0.5 Hz). Muscle biopsies (vastus lateralis) were taken before and immediately after exercise and were analyzed for maximal in vitro Na+-K+-ATPase (K+-stimulated 3-O-methylfluoroscein phosphatase) activity. Resting samples were analyzed for [3H]ouabain binding site content, which was 16.6 and 18.3% higher (P < 0.05) in ET than RT and UT, respectively (UT 311 ± 41, RT 302 ± 52, ET 357 ± 29 pmol/g wet wt). 3-O-methylfluoroscein phosphatase activity was depressed at fatigue by −13.8 ± 4.1% (P < 0.05), with no differences between groups (UT −13 ± 4, RT −9 ± 6, ET −22 ± 6%). During incremental exercise, ET had a lower ratio of rise in plasma K+ concentration to work than UT (P < 0.05) and tended (P = 0.09) to be lower than RT (UT 18.5 ± 2.3, RT 16.2 ± 2.2, ET 11.8 ± 0.4 nmol · l−1 · J−1). In conclusion, maximal in vitro Na+-K+-ATPase activity was depressed with fatigue, regardless of training state, suggesting that this may be an important determinant of fatigue.
Language eng
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 ©2002, American Physiological Society
Persistent URL http://hdl.handle.net/10536/DRO/DU:30033447

Document type: Journal Article
Collections: Faculty of Health
School of Exercise and Nutrition Sciences
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