Submitted on December 9, 2002
Accepted on May 22, 2003
A compartmental model of magnesium metabolism in healthy men based on two stable isotope tracers
Magalie Sabatier1, Frederic Pont2, Maurice J Arnaud1*, and Judith R Turnlund3
1 Nestle Water Institute, Vittel, France
2 IFR 30, INSERM, Mass spectrometry unit, Toulouse, France
3 US Department of Agriculture, Western Human Nutrition Research Center, Davis, CA, USA
* To whom correspondence should be addressed. E-mail: Maurice.arnaud{at}waters.nestle.com.
The aim of this study was to build a compartmental model of magnesium kinetics using data collected from 6 healthy adult men following oral administration of 26Mg and intravenous administration of 25Mg. Blood, urine and feces were collected for 12 days following administration of the isotopes. Isotopic ratios were determined by Inductively Coupled Plasma-Mass Spectrometry. Data were analyzed for each subject using the SAAMII.
We began with a compartmental model proposed by Avioli and Berman (5) 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 2 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.
