Document Detail

Intracellular acidification and volume increases explain R(2) decreases in exercising muscle.
MedLine Citation:
PMID:  11754438     Owner:  NLM     Status:  MEDLINE    
Exercise-induced decreases in the (1)H transverse relaxation rate (R(2)) of muscle have been well documented, but the mechanism remains unclear. In this study, the hypothesis was tested that R(2) decreases could be explained by pH decreases and apparent intracellular volume (V(i)') increases. (31)P and (1)H spectroscopy, biexponential R(2) analysis, and imaging were performed prior to and following fatiguing exercise in iodoacetate-treated (IAA, to inhibit glycolysis), NaCN-treated (to inhibit oxidative phosphorylation), and untreated frog gastrocnemii. In all exercised muscles, the apparent intracellular R(2) (R(2i)') and pH decreased, while intracellular osmolytes and V(i)' increased. These effects were larger in NaCN-treated and untreated muscles than in IAA-treated muscles. Multiple regression analysis showed that pH and V(i)' changes explain 70% of the R(2i)' variance. Separate experiments in unexercised muscles demonstrated causal relationships between pH and R(2i)' and between V(i)' and R(2i)'. These data indicate that the R(2) change of exercise is primarily an intracellular phenomenon caused by the accumulation of the end-products of anaerobic metabolism. In the NaCN-treated and untreated muscles, the R(2i)' change increased as field strength increased, suggesting a role for pH-modulated chemical exchange.
Bruce M Damon; Carl D Gregory; Kristen L Hall; Heather J Stark; Vikas Gulani; M Joan Dawson
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine     Volume:  47     ISSN:  0740-3194     ISO Abbreviation:  Magn Reson Med     Publication Date:  2002 Jan 
Date Detail:
Created Date:  2001-12-26     Completed Date:  2002-02-05     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8505245     Medline TA:  Magn Reson Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  14-23     Citation Subset:  IM    
Copyright Information:
Copyright 2002 Wiley-Liss, Inc.
Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, USA.
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MeSH Terms
Hydrogen-Ion Concentration
Iodoacetates / pharmacology
Magnetic Resonance Spectroscopy* / diagnostic use
Muscle Contraction / physiology*
Muscle, Skeletal / drug effects,  physiology*
Rana pipiens
Grant Support
5 F30 MH11041/MH/NIMH NIH HHS; 5 P41 RR05964/RR/NCRR NIH HHS; T32 CA09067/CA/NCI NIH HHS
Reg. No./Substance:

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