Fatigue depresses maximal in vitro skeletal muscle Na+-K+-ATPase activity in untrained and trained individuals
| Autor: | Jia Li Li, Xiao N. Wang, Termboon Sangkabutra, Michael Carey, Steve E Selig, Steve F. Fraser, Keld Kjeldsen, Simon Sostaric, Michael J. McKenna |
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| Rok vydání: | 2002 |
| Předmět: |
Adult
Male medicine.medical_specialty Weight Lifting Physiology Physical exercise Diaphragm pump In Vitro Techniques NA K EXCHANGING ATPASE Oxygen Consumption Reference Values Physiology (medical) Internal medicine medicine Humans Na+/K+-ATPase Muscle Skeletal Na k atpase activity Blood Volume Physical Education and Training Chemistry Skeletal muscle In vitro medicine.anatomical_structure Endocrinology Reference values Muscle Fatigue Physical Endurance Potassium Female Sodium-Potassium-Exchanging ATPase |
| Zdroj: | Journal of Applied Physiology. 93:1650-1659 |
| ISSN: | 1522-1601 8750-7587 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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