Aqueous shift reagents were used to clearly distinguish intra- and extracellular 23Na-nuclear magnetic resonance (NMR) signals in samples consisting of whole blood or suspensions of washed human erythrocytes (both fresh and outdated). The lanthanide chelates Dy(PPP)27- and Tm(TTHA)3- were used to shift the extracellular signals upfield, and Dy(TTHA)3- and Tm(PPP)27- were similarly used to shift extracellular resonance downfield. The absolute intensities of the signals were used along with the measured hematocrit to simultaneously determine the intra- and extracellular Na+ concentrations. The results were generally within 5% of the values determined by more time-consuming centrifugation-flame emission photometry measurements on the same samples. Thus the 23Na-NMR signals from both intra- and extracellular cations suffer no NMR invisibility within experimental error. The lower level of intracellular Na+ in fresh erythrocytes (<12 mM) is easily distinguished from the higher level (~30 mM) in erythrocytes that have been stored (in the cold) outside the body for some weeks.
ASJC Scopus subject areas
- Cell Biology