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The longitudinal relaxation time ( T 1 ) of the intracellular 23 Na NMR signal in the isolated perfused rat heart during hypoxia and reoxygenation
Author(s) -
Prince Lawrence S.,
Miller Sandra K.,
Pohost Gerald M.,
Elgavish Gabriel A.
Publication year - 1992
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910230218
Subject(s) - intracellular , chemistry , reagent , isotopes of sodium , hypoxia (environmental) , ion , sodium , nuclear magnetic resonance , polyelectrolyte , biophysics , analytical chemistry (journal) , kinetics , time constant , chromatography , oxygen , biochemistry , physics , biology , polymer , organic chemistry , electrical engineering , engineering , quantum mechanics
Each of six perfused rat hearts was subjected to 30 min of hypoxia followed by 60 min of reoxygenation. Inversion‐recovery data on the intracellular Na NMR signal, differentiated by a shift reagent, 6 m M Dy(PPP) 2 , were obtained every 5 min, and T 1 values were calculated. The T 1 of the intracellular Na signal did not show any significant change either during hypoxia or upon reoxygenation, although the level of Na i increased about 50%. Such an increase of total Na i , is expected to reduce the observed relaxation rate by diluting the fraction of Na i , ions that interact with intracellular polyelectrolytes. The observed constancy of T 1 in our study is explained on the basis of the typical values of the dissociation constants of sodium ions, in aqueous solutions, in interaction with polyelectrolytes. Although the constancy of intracellular sodium T 1 during hypoxia may preclude the utilization of T 1 , weighting for the monitoring of pathology, its determination could be important for setting optimal acquisition times in high time‐resolution experiments. © 1992 Academic Press, Inc.