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Assessment of magnesium concentrations by 31 P NMR in vivo
Author(s) -
Halvorson H. R.,
Vande Linde A. M. Q.,
Helpern J. A.,
Welch K. M. A.
Publication year - 1992
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.1940050202
Subject(s) - chemical shift , phosphocreatine , in vivo , chemistry , magnesium , spectral line , nmr spectra database , ion , biology , organic chemistry , energy metabolism , physics , microbiology and biotechnology , astronomy , endocrinology
31 P NMR spectra obtained in vivo reveal the presence of a few reasonably well defined chemical species, namely, ATP, orthophosphate (P i ), and, in brain, phosphocreatine. The chemical shifts of these resonances respond to changes in concentrations of ions such as H + and Mg 2+ in a manner that depends on both the chemical shifts intrinsic to individual complexes and the formation or binding constants for the several complexes. Values of the appropriate formation constants are well established in the literature. We have derived estimates of the chemical shifts intrinsic to the individual complexes by analyzing high resolution spectra of solutions whose composition brackets the domain of physiological relevance. This provides information sufficient to estimate intracellular concentrations of H + and Mg 2+ from chemical shifts seen with in vivo spectra. The primary finding is an estimate of 0.3 m M for the concentration of free magnesium in human brain. Differing values are obtained from other tissues.