Influence of dietary magnesium in experimental phosphate depletion: bone and soft tissue mineral changes.

We studied weanling rats fed 0.06% (group 1) and 0.10% (group II) magnesium (Mg) during phosphate depletion (PD) in order to evaluate the role of Mg in the bone, soft tissue, and serum changes of PD. The following results were obtained: 1) serum Mg remained stable in the face of a negative Mg balance; 2) the hypercalcemic and hypercalciuric response to PD was the same in both groups; 3) bone Mg content was decreased with PD in both groups and was associated with a significant decrease in bone calcium and phosphorus. We conclude that: 1) the hypomagnesemia of PD is dependent mainly on the dietary intake of Mg; 2) the hypercalcemia and hypercalciuria of PD are not caused by primary changes in Mg homeostasis; 3) low-dietary Mg during PD may cause a defect in soft tissue utilization of P in the growing rat.