ABSTRACT
Magnesium is the fourth most abundant cation in the body and, after potassium, the most abundant in the cell. As the essential metal in chlorophyll, magnesium has a central role in life processes. Reexamination of magnesium transport in gastrointestinal mucosal cells and across isolated membranes would only add to understanding of magnesium absorption mechanisms, it could also provide insight into mechanism of membrane transport of magnesium and the processes by which cells maintain magnesium homeostasis. Although the exchangeable magnesium pool decreases with age, and as a result of magnesium depletion, the linear relationship between the exchangeable magnesium pool and plasma or medium magnesium concentration has been demonstrated under various conditions, including magnesium deficiency and excess. The effects of magnesium depletion have been studied most intensively in rats, however, and much of current understanding of the roles of magnesium in animals rests on observations made in rats.
