Research Repository

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

Fraser, Steve F, Li, Jia Li, Carey, Michael F, Wang, Xiao N, Sangkabutra, Termboon, Sostaric, Simon, Selig, Steve E, Kjeldsen, Keld and McKenna, Michael ORCID: 0000-0001-9998-0093 (2002) Fatigue depresses maximal in vitro skeletal muscle Na+-K+-ATPase activity in untrained and trained individuals. Journal of applied physiology, 93. pp. 1650-1659. ISSN 8750-7587

Full text for this resource is not available from the Research Repository.

Abstract

Fatigue depresses maximal in vitro skeletal muscle Na+-K+- ATPase activity in untrained and trained individuals. J Appl Physiol 93: 1650–1659, 2002. First published July 12, 2002; 10.1152/japplphysiol.01247.2001.—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.

Item Type: Article
Uncontrolled Keywords: 3-O-methylfluoroscein phosphatase, exercise, Na+-K+ pump, potassium
Subjects: RFCD Classification > 240000 Physical Sciences
Faculty/School/Research Centre/Department > Centre for Ageing, Rehabilitation, Exercise & Sport Science (CARES)
Depositing User: Ms Phung T Tran
Date Deposited: 17 Oct 2008 05:10
Last Modified: 16 Apr 2019 06:36
URI: http://vuir.vu.edu.au/id/eprint/1053
ePrint Statistics: View download statistics for this item
Citations in Scopus: 63 - View on Scopus

Repository staff only

View Item View Item

Search Google Scholar