Extracellular volume and transsarcolemmal proton movement during ischemia and reperfusion: a 31P NMR spectroscopic study of the isovolumic rat heart.

K. Clarke, L. C. Stewart, S. Neubauer, J. A. Balschi, T. W. Smith, J. S. Ingwall, J. F. Nédélec, S. M. Humphrey, A. G. Kléber, Charles Jr Springer

Research output: Contribution to journalArticle

60 Scopus citations


We have measured, directly and simultaneously, changes in extracellular volume and intra- and extracellular pH during ischemia in the isolated rat heart using 31P NMR spectroscopy. Hearts were perfused with buffer containing 15 mM sodium phenylphosphonate at pH 7.4. 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 31P 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.

Original languageEnglish (US)
Pages (from-to)278-286
Number of pages9
JournalNMR in Biomedicine
Issue number4
Publication statusPublished - Jul 1993
Externally publishedYes


ASJC Scopus subject areas

  • Biophysics
  • Spectroscopy
  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this