Document Detail

Increasing temperature speeds intracellular PO2 kinetics during contractions in single Xenopus skeletal muscle fibers.
MedLine Citation:
PMID:  23152111     Owner:  NLM     Status:  MEDLINE    
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.
S Koga; R C I Wüst; B Walsh; C A Kindig; H B Rossiter; M C Hogan
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2012-11-14
Journal Detail:
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:
Created Date:  2013-01-02     Completed Date:  2013-03-07     Revised Date:  2014-01-09    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R59-66     Citation Subset:  IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Adenosine Triphosphate / metabolism
Body Temperature*
Mitochondria, Muscle / physiology
Muscle Contraction / physiology*
Muscle Fibers, Skeletal / physiology*
Oxygen / analysis,  physiology*
Oxygen Consumption / physiology
Xenopus laevis / physiology*
Grant Support
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
Reg. No./Substance:
8L70Q75FXE/Adenosine Triphosphate; S88TT14065/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Effect of chronic perinatal hypoxia on the role of rho-kinase in pulmonary artery contraction in new...
Next Document:  Differential expression of the pro-natriuretic peptide convertases corin and furin in experimental h...