Discrimination of intra- and extracellular 23Na+ signals in yeast cell suspensions using longitudinal magnetic resonance relaxography

Yajie Zhang, Marie Poirer-Quinot, Charles S. Springer, James A. Balschi

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

This study tested the ability of MR relaxography (MRR) to discriminate intra- (Nai+) and extracellular (Nae+) 23Na+ signals using their longitudinal relaxation time constant (T1) values. Na +-loaded yeast cell (Saccharomyces cerevisiae) suspensions were investigated. Two types of compartmental 23Na+ T 1 differences were examined: a selective Nae+ T1 decrease induced by an extracellular relaxation reagent (RRe), GdDOTP 5-; and, an intrinsic T1 difference. Parallel studies using the established method of 23Na MRS with an extracellular shift reagent (SRe), TmDOTP5-, were used to validate the MRR measurements. With 12.8 mM RRe, the 23Nae+ T1 was 2.4 ms and the 23Nai+ T1 was 9.5 ms (9.4T, 24 °C). The Na+ amounts and spontaneous efflux rate constants were found to be identical within experimental error whether measured by MRR/RRe or by MRS/SR e. Without RRe, the Na+-loaded yeast cell suspension 23Na MR signal exhibited two T1 values, 9.1 (±0.3) ms and 32.7 (±2.3) ms, assigned to 23Nai+ and 23Nae+, respectively. The Nai+ content measured was lower, 0.88 (±0.06); while Nae+ was higher, 1.43 (±0.12) compared with MRS/SRe measures on the same samples. However, the measured efflux rate constant was identical. T1 MRR potentially may be used for Nai+ determination in vivo and Na+ flux measurements; with RRe for animal studies and without RRe for humans.

Original languageEnglish (US)
Pages (from-to)28-37
Number of pages10
JournalJournal of Magnetic Resonance
Volume205
Issue number1
DOIs
StatePublished - Jul 2010

Keywords

  • Intracellular Na
  • Na MR
  • Relaxation reagent
  • T relaxography

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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