In Vivo Assessment of Free Magnesium Concentration in Human Brain by 31P MRS. A New Calibration Curve Based on a Mathematical Algorithm
✍ Scribed by S. Iotti; C. Frassineti; L. Alderighi; A. Sabatini; A. Vacca; B. Barbiroli
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 890 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0952-3480
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✦ Synopsis
Free cytosolic [Mg'] can be assessed in vivo by "P MRS from the chemical shift of &ATP which in turn depends on the fraction of total ATP complexed to Mg2+ ions. The reliability of these in vivo measurements depends on the availability of an appropriate in vitro calibration to determine the limits of chemical shifts of unbound ATP and Mg-ATP complexes, using solutions that mimic the in vivo cytosolic conditions as far as possible. We used an algorithm and software to allow a quantitative definition of the M$'-binding molecules to build a semi-empirical equation that correlates the chemical shift of the PATP signal to the [Mg'] taking into account the amount of Mg2+ bound to all other constituents in solution. Our experiments resulted in a simple and reliable equation directly usable to assess in vivo the free cytosolic magnesium concentration of human brain by 31P MRS. Our method is also flexible enough to make it suitable for in vivo measurements of [Mg'] in other organs and tissues.
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MATERIALSAND METHODS
Materials
Adenosine triphosphate phosphocreatine disodium salts and creatine (99% purity) were purchased from Sigma Chemical Co., U.S.A; MgCI,, K,HP04, KCl and 2H,0 (99% purity) were from Merck (Darmstadt, Germany).