A compartmental model of magnesium metabolism in healthy men based on two stable isotope tracers

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology Vol. 285; no. 3; pp. 656 - R663
• Main Authors: Sabatier, Magalie, Pont, Frederic, Arnaud, Maurice J, Turnlund, Judith R
• Format: Journal Article
• Language: English
• Published: United States 01.09.2003
• Subjects: Adult; Feces; Humans; Intestinal Absorption - physiology; Isotopes; Kinetics; Magnesium - blood; Magnesium - pharmacokinetics; Magnesium - urine; Male; Mass Spectrometry; Models, Biological
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00749.2002

1 Nestle Water Institute, 88804 Vittel; 2 Mass Spectrometry Unit, Institut National de la Santé et de la Recherche Médicale, 31024, Toulouse, France; and 3 Western Human Nutrition Research Center, United States Department of Agriculture, University of California, Davis, California 95616 Submitted 9 December 2002 ; accepted in final form 22 May 2003 The aim of this study was to build a compartmental model of magnesium (Mg) kinetics by using data collected from six healthy adult men after oral administration of 26 Mg and intravenous administration of 25 Mg. Blood, urine, and feces were collected for 12 days after administration of the isotopes. Isotopic ratios were determined by inductively coupled plasma-mass spectrometry. Data were analyzed for each subject using SAAMII. We began with a compartmental model previously proposed (Avioli LV and Berman M. J Appl Physiol 21: 1688-1694, 1966) and developed an alternative approach to resolve the discrepancy between model-predicted curves and experimental data. This analysis enables the exploration of 25% of total body Mg that exchanges rapidly from plasma compartment with two extraplasma pools. One of the extraplasma compartments contains 80% of the exchangeable Mg with a transport rate of 48 ± 13 mg/h. The second exchanges 179 ± 88 mg of Mg/h. The model permitted estimation of kinetic parameters as well as fractional Mg absorption and fecal endogenous excretion. magnesium absorption; magnesium fecal endogenous excretion; inductively coupled plasma-mass spectrometry Address for reprint requests and other correspondence: M. J. Arnaud, Nestle Water Institute, BP 101, 88804, Vittel Cedex, France.