Premium
Extracellular volume and transsarcolemmal proton movement during ischemia and reperfusion: A 31 P NMR spectroscopic study of the isovolumic rat heart
Author(s) -
Clarke Kieran,
Stewart Laura C.,
Neubauer Stefan,
Balschi James A.,
Smith Thomas W.,
Ingwall Joanne S.,
Nédélec JeanFrançois,
Humphrey Stuart M.,
Kléber André G.,
Springer Charles S.
Publication year - 1993
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1940060407
Subject(s) - extracellular , extracellular fluid , chemistry , ischemia , intracellular ph , intracellular , sodium , biophysics , biochemistry , medicine , biology , organic chemistry
We have measured, directly and simultaneously, changes in extracellular volume and intra‐ and extracellular pH during ischemia in the isolated rat heart using 31 P NMR spectroscopy. Hearts were perfused with buffer containing 15 mM sodium phenylphosphonate at pH7.4. Wash in and wash out experiments showed that phenylphosphonate entered only the extracellular (interstitial, vascular and chamber) space of the heart and had no adverse effects on myocardial energetics, contractile function or coronary flow rate. Hearts were subjected to 28 min of total, global ischemia, during which the phenylphosphonate resonance area in the 31 P NMR spectra decreased by 83%, indicating that extracellular fluid had moved rapidly from the heart to the bath surrounding the heart, partly as a result of vascular collapse. A separate, morphological study confirmed that 95% of the vasculature had collapsed by 28 min ischemia. Intra‐ and extracellular pH were determined from the chemical shifts of the P i and the phenylphosphonate resonances, respectively. In the pre‐ischemic rat heart, intracellular pH was 7.15±0.03 and extracellular pH was 7.39±0.03. By 4 min of ischemia, intra‐ and extracellular pH were the same and decreased concomitantly throughout the remainder of ischemia to final values of 6.09±0.19 and 6.16±0.23, respectively. On reperfusion, the extracellular volume and pH returned to pre‐ischemic levels within 1 min, but restoration of intracellular pH took >2.5 min. Thus, a large volume of extracellular fluid moves out of the rat heart to the surrounding bath and the intra‐ and extracellular pH become the same during total, global ischemia.