Document Detail


NMR visibility of Pi in perfused rat hearts is affected by changes in substrate and contractility.
MedLine Citation:
PMID:  1510146     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Nuclear magnetic resonance (NMR) spectroscopy does not always detect the total metabolite content in isolated perfused rat hearts. Alterations in NMR peak areas therefore could be caused by a change either in the metabolite content per se or in its NMR visibility. We have therefore compared the ATP, phosphocreatine (PCr), and Pi content of hearts, as determined by 31P-NMR spectroscopy, with the total, chemically determined ATP, PCr, and Pi contents of the same hearts to determine the fractions, if any, that are NMR invisible under different perfusion conditions. The three perfusion buffers used contained 1) glucose, 2) glucose plus high K+, and 3) pyruvate. Fully relaxed 31P-NMR spectra were collected during the final 10 min of perfusion in each group, and the ATP, PCr, and Pi contents were quantified using methylene diphosphonate as an external standard. The hearts were then freeze-clamped and chemically assayed for ATP, PCr, and Pi. Under all three conditions, the NMR-determined ATP and PCr contents were almost identical to the chemically determined values. However, only a portion of the chemically determined Pi was NMR visible. During perfusion with glucose-containing buffer, 39 +/- 8% of the total Pi was NMR visible, and this decreased to 12 +/- 2% (P less than 0.01) during K+ arrest and to 9 +/- 5% (P less than 0.01) during perfusion with pyruvate-containing buffer. In conclusion, whereas the total cellular content of ATP and PCr is always NMR visible during normoxic perfusion, alterations in substrate and contractile status can change the fraction of NMR-visible Pi.
Authors:
P B Garlick; R M Townsend
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  263     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1992 Aug 
Date Detail:
Created Date:  1992-09-22     Completed Date:  1992-09-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H497-502     Citation Subset:  IM    
Affiliation:
Division of Radiological Sciences, United Medical School, Guy's Hospital, London, United Kingdom.
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MeSH Terms
Descriptor/Qualifier:
Adenosine Triphosphate / metabolism
Animals
Magnetic Resonance Spectroscopy*
Male
Myocardial Contraction / physiology*
Myocardium / metabolism*
Perfusion
Phosphates / metabolism*
Phosphocreatine / metabolism
Phosphorus
Rats
Rats, Inbred Strains
Substrate Specificity
Time Factors
Chemical
Reg. No./Substance:
0/Phosphates; 56-65-5/Adenosine Triphosphate; 67-07-2/Phosphocreatine; 7723-14-0/Phosphorus

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


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