| Increasing temperature speeds intracellular PO2 kinetics during contractions in single Xenopus skeletal muscle fibers. | |
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MedLine Citation:
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PMID: 23152111 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Precise determination of the effect of muscle temperature (T(m)) on mitochondrial oxygen consumption kinetics has proven difficult in humans, in part due to the complexities in controlling for T(m)-related variations in blood flow, fiber recruitment, muscle metabolism, and contractile properties. To address this issue, intracellular Po(2) (P(i)(O(2))) was measured continuously by phosphorescence quenching following the onset of contractions in single Xenopus myofibers (n = 24) while controlling extracellular temperature. Fibers were subjected to two identical contraction bouts, in random order, at 15°C (cold, C) and 20°C (normal, N; n = 12), or at N and 25°C (hot, H; n = 12). Contractile properties were determined for every contraction. The time delay of the P(i)(O(2)) response was significantly greater in C (59 ± 35 s) compared with N (35 ± 26 s, P = 0.01) and H (27 ± 14 s, P = 0.01). The time constant for the decline in P(i)(O(2)) was significantly greater in C (89 ± 34 s) compared with N (52 ± 15 s; P < 0.01) and H (37 ± 10 s; P < 0.01). There was a linear relationship between the rate constant for P(i)(O(2)) kinetics and T(m) (r = 0.322, P = 0.03). Estimated ATP turnover was significantly greater in H than in C (P < 0.01), but this increased energy requirement alone with increased T(m) could not account for the differences observed in P(i)(O(2)) kinetics among conditions. These results demonstrate that P(i)(O(2)) kinetics in single contracting myofibers are dependent on T(m), likely caused by temperature-induced differences in metabolic demand and by temperature-dependent processes underlying mitochondrial activation at the start of muscle contractions. |
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Authors:
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S Koga; R C I Wüst; B Walsh; C A Kindig; H B Rossiter; M C Hogan |
Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't Date: 2012-11-14 |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: 304 ISSN: 1522-1490 ISO Abbreviation: Am. J. Physiol. Regul. Integr. Comp. Physiol. Publication Date: 2013 Jan |
Date Detail:
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Created Date: 2013-01-02 Completed Date: 2013-03-07 Revised Date: 2013-04-16 |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: United States |
Other Details:
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Languages: eng Pagination: R59-66 Citation Subset: IM |
Affiliation:
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Applied Physiology Laboratory, Kobe Design University, Japan. s-koga@kobe-du.ac.jp |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adenosine Triphosphate
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metabolism Animals Body Temperature* Female Mitochondria, Muscle / physiology Muscle Contraction / physiology* Muscle Fibers, Skeletal / physiology* Oxygen / analysis, physiology* Oxygen Consumption / physiology Xenopus laevis / physiology* |
| Grant Support | |
ID/Acronym/Agency:
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AR-053219/AR/NIAMS NIH HHS; AR-40155/AR/NIAMS NIH HHS; AR-48461/AR/NIAMS NIH HHS; BB/F019521/1//Biotechnology and Biological Sciences Research Council; BB/I024798/1//Biotechnology and Biological Sciences Research Council; HL-17731/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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56-65-5/Adenosine Triphosphate; 7782-44-7/Oxygen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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