dc.date.accessioned | 2014-04-10T16:02:41Z | |
dc.date.available | 2014-04-10T16:02:41Z | |
dc.date.created | 2013-10-28T13:46:38Z | |
dc.date.issued | 2013 | |
dc.identifier.citation | Hortemo, Kristin Halvorsen Munkvik, Morten Lunde, Per Kristian Sejersted, Ole M . Multiple Causes of Fatigue during Shortening Contractions in Rat Slow Twitch Skeletal Muscle. PLoS ONE. 2013, 8(8) | |
dc.identifier.uri | http://hdl.handle.net/10852/39075 | |
dc.description.abstract | Fatigue in muscles that shorten might have other causes than fatigue during isometric contractions, since both cross-bridge cycling and energy demand are different in the two exercise modes. While isometric contractions are extensively studied, the causes of fatigue in shortening contractions are poorly mapped. Here, we investigate fatigue mechanisms during shortening contractions in slow twitch skeletal muscle in near physiological conditions. Fatigue was induced in rat soleus muscles with maintained blood supply by in situ shortening contractions at 37°C. Muscles were stimulated repeatedly (1 s on/off at 30 Hz) for 15 min against a constant load, allowing the muscle to shorten and perform work. Fatigue and subsequent recovery was examined at 20 s, 100 s and 15 min exercise. The effects of prior exercise were investigated in a second exercise bout. Fatigue developed in three distinct phases. During the first 20 s the regulatory protein Myosin Light Chain-2 (slow isoform, MLC-2s) was rapidly dephosphorylated in parallel with reduced rate of force development and reduced shortening. In the second phase there was degradation of high-energy phosphates and accumulation of lactate, and these changes were related to slowing of muscle relengthening and relaxation, culminating at 100 s exercise. Slowing of relaxation was also associated with increased leak of calcium from the SR. During the third phase of exercise there was restoration of high-energy phosphates and elimination of lactate, and the slowing of relaxation disappeared, whereas dephosphorylation of MLC-2s and reduced shortening prevailed. Prior exercise improved relaxation parameters in a subsequent exercise bout, and we propose that this effect is a result of less accumulation of lactate due to more rapid onset of oxidative metabolism. The correlation between dephosphorylation of MLC-2s and reduced shortening was confirmed in various experimental settings, and we suggest MLC-2s as an important regulator of muscle shortening.
Copyright 2013 Hortemo et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License. | en_US |
dc.language | EN | |
dc.language.iso | en | en_US |
dc.publisher | Public Library of Science (PLoS) | |
dc.relation.ispartof | Hortemo, Kristin Halvorsen (2016) Fatigue mechanisms of shortening skeletal muscle: Protein phosphorylation and O-GlcNAcylation with emphasis on regulatory myosin light chain (MLC2). Doctoral thesis. http://urn.nb.no/URN:NBN:no-56590 | |
dc.relation.uri | http://urn.nb.no/URN:NBN:no-56590 | |
dc.title | Multiple Causes of Fatigue during Shortening Contractions in Rat Slow Twitch Skeletal Muscle | en_US |
dc.type | Journal article | en_US |
dc.creator.author | Hortemo, Kristin Halvorsen | |
dc.creator.author | Munkvik, Morten | |
dc.creator.author | Lunde, Per Kristian | |
dc.creator.author | Sejersted, Ole M | |
cristin.unitcode | 185,53,15,10 | |
cristin.unitname | Institutt for eksperimentell medisinsk forskning | |
cristin.ispublished | true | |
cristin.fulltext | original | |
cristin.qualitycode | 1 | |
dc.identifier.cristin | 1060946 | |
dc.identifier.bibliographiccitation | info:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=PLoS ONE&rft.volume=8&rft.spage=&rft.date=2013 | |
dc.identifier.jtitle | PLoS ONE | |
dc.identifier.volume | 8 | |
dc.identifier.issue | 8 | |
dc.identifier.pagecount | 15 | |
dc.identifier.doi | http://dx.doi.org/10.1371/journal.pone.0071700 | |
dc.identifier.urn | URN:NBN:no-43941 | |
dc.type.document | Tidsskriftartikkel | en_US |
dc.type.peerreviewed | Peer reviewed | |
dc.source.issn | 1932-6203 | |
dc.identifier.fulltext | Fulltext https://www.duo.uio.no/bitstream/handle/10852/39075/2/journal.pone.0071700.pdf | |
dc.type.version | PublishedVersion | |
cristin.articleid | e71700 | |