Document Detail


Evaluation of multiple-quantum-filtered 23Na NMR in monitoring intracellular Na content in the isolated perfused rat heart in the absence of a chemical-shift reagent.
MedLine Citation:
PMID:  9245637     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The feasibility of employing triple-quantum-filtered (TQF) or double-quantum-filtered (DQF) 23Na NMR spectra to monitor intracellular Na (Nain) content in isolated rat hearts perfused in the absence of a chemical-shift reagent (SR) was investigated. This necessitated characterization of the following: first, the pool of Nain represented by the intracellular TQF (TQFin) spectrum; second, the maximum extent to which altered transverse relaxation times affect TQFin spectral amplitudes; and finally, the situations for which the SR-free method can reliably be applied. The rates of increase in peak amplitudes of both intracellular TQF spectra, adjusted for changes in both fast (T2f) and slow (T2s) transverse relaxation times, and intracellular single-quantum (SQin) spectra were identical during no-flow ischemia, indicating that TQFin and SQin spectra represent the same Nain population. Addition of an Na/K ATPase inhibitor, ouabain (>/=500 microM), and no-flow ischemia induced similar rates of increase of Nain content. However, the Nain level for which the T2 values started to increase was lower for ischemic (<140% of preischemic values) than for ouabain-exposed (>165%) hearts, which is consistent with the known earlier onset of intracellular swelling in ischemic hearts. Exposure of hearts to hyperosmotic perfusate (200 mM sucrose) increased [Nain], due to a decreased cell volume and an unchanged Nain content, but caused a decrease in T2 values, a trend opposite to that observed with exposure of hearts to ouabain or ischemia. T2 values therefore consistently correlated only with cell volume, not with Nain content or concentration, indicating an important role for intracellular macromolecule concentration in modulating transverse relaxation behavior. The combined effect of ischemia-induced increases in T2 values and their inhomogeneous broadened forms was an approximately 6% overestimation of Nain content from amplitudes of SR-aided TQFin spectra, indicating negligible effect of transverse relaxation-dependent alterations on TQFin spectral amplitudes. Thus, Nain content may be reliably determined from SR-free TQF spectra when the contribution from extracellular Na does not appreciably vary, such as during constant pressure perfusion. Following complete reduction in perfusion pressure, both SR-free TQF and DQF spectra respond to increases in Nain content. However, SR-free DQF NMR provides an estimate of Nain content much closer to that provided by the SR-aided method, due to the appreciable decrease of the extracellular DQF signal resulting from destructive interference between second- and third-rank tensors.
Authors:
J S Tauskela; J M Dizon; J Whang; J Katz
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Journal of magnetic resonance (San Diego, Calif. : 1997)     Volume:  127     ISSN:  1090-7807     ISO Abbreviation:  J. Magn. Reson.     Publication Date:  1997 Jul 
Date Detail:
Created Date:  1997-09-04     Completed Date:  1997-09-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9707935     Medline TA:  J Magn Reson     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  115-27     Citation Subset:  IM    
Affiliation:
Division of Cardiology, Columbia University, New York, New York 10032, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Magnetic Resonance Spectroscopy / methods*
Male
Myocardial Ischemia / metabolism
Myocardium / metabolism*
Ouabain / pharmacology
Rats
Rats, Wistar
Sodium / metabolism*
Chemical
Reg. No./Substance:
630-60-4/Ouabain; 7440-23-5/Sodium

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


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