Intestinal Transport of Calcium and Phosphate in Experimental Magnesium Deficiency. ∗

Abstract

Summary

The concentrative transport of calcium by everted intestinal loops in vitro and the permeability of the small intestinal wall to this ion were determined in intestinal preparations from vitamin D deficient and vitamin D treated magnesium deficient and control rats. These experiments indicate that concentrative transport of calcium by rat small intestine in vitro is altered by the presence or absence of magnesium in the medium but not by magnesium depletion of the animals. The permeability to calcium of the intestinal preparations was not influenced by magnesium deficiency. The effects of magnesium depletion of the rat and of the presence of magnesium in the medium on concentrative transport of inorganic phosphate by the small intestine in vitro were also studied. Concentrative transport of phosphate by intestinal loops incubated in Mg++ containing buffer was less than that by those incubated in Mg++ free buffer. Intestinal loop preparations from magnesium deficient animals transferred phosphate to a greater extent than those obtained from control rats; this difference was observed both in the presence and absence of Mg++ in the buffer solution. Magnesium deficiency in the rat also reduced the concentration of serum phosphorus and increased the excretion of phosphate in the urine. These findings are consistent with the theory that magnesium influences the phosphate transport systems which control phosphate concentrations in extracellular fluids.