Magnesium transport from aqueous solutions across Caco-2 cells--an experimental model for intestinal bioavailability studies. Physiological considerations and recommendations.

The Caco-2 cell model is gaining more and more importance as an in vitro method to study intestinal nutrient bioavailability from foods. In a previous article we presented evidence that fractional Mg2+ transport from different aqueous solutions containing differing amounts of magnesium varies considerably in some cases. In the present article we discuss the role of electrolytes, such as calcium and the anions HCO3-, SO4(2-) and Cl-, in modulating magnesium absorption. Another purpose of this manuscript is to give recommendations, based mainly on physiological knowledge, which can be helpful when planning and conducting intestinal bioavailability studies using either the Caco-2 culture system or other in vitro models in order to achieve nearly similar conditions as in vivo.