Goodman, Craig ORCID: 0000-0002-5874-7743, Hayes, Alan ORCID: 0000-0003-1398-3694 and McKenna, Michael ORCID: 0000-0001-9998-0093 (2009) Dissociation between force and maximal Na+, K+-ATPase activity in rat fast-twitch skeletal muscle with fatiguing in vitro stimulation. European Journal of Applied Physiology, 105 (4). pp. 575-583. ISSN 1439-6319

Abstract

This study investigated whether high frequency in vitro stimulation of rat fast-twitch extensor digitorum longus muscle depresses Na+, K+-ATPase (NKA) activity as measured by the maximal in vitro 3-O-MFPase assay. EDL muscles subjected to 10 s continuous 100 Hz stimulation reduced tetanic force by 51.8 +/- 5.1% which recovered to 81.2 +/- 6.1% after 1 min and remained stable over 1 h recovery period. A second bout reduced force by 50.3 +/- 3.8% of initial but had no eVect on 3-O-MFPase activity. Three minutes of intermittent stimulation (1 s at 100 Hz and 4 s recovery) resulted in 87.0 +/- 2.8% decline force with slow recovery (62.7 +/- 5.8% of initial after 1 h). The second 3-min bout reduced force by 83.3 +/- 3.6% of initial with no change in maximal 3-O-MFPase activity. These Wndings contrast previous human studies where fatiguing voluntary exercise depresses maximal NKA activity. This suggests that NKA in rat fast-twitch muscle is resistant to fatigue-induced inactivation under these conditions tions. Furthermore, the loss of force with fatigue was not related to depressed maximal NKA activity.

Search Google Scholar

Repository staff login