Intestinal absorption of phosphate: action of protein synthesis inhibitors and glucocorticoids in the rat.

The effect of actinomycin D, cycloheximide and glucocorticoids on the intestinal absorption of phosphate was studied. The effective intestinal absorption of 32P and 47Ca was determined simultaneously in intact rats in vivo using a whole body counter. Both, actinomycin D and cycloheximide caused a significant diminution of the intestinal absorption of phosphate whereas calcium absorption was not altered. Experiments with the in situ ligated loop technique were performed to eliminate the possibility that the action of the protein synthesis inhibitors could be due to an altered intestinal motility effect. Phosphate absorption was also significantly diminished under this condition. On the other hand, the administration of glucocorticoids produced a significant inhibition of phosphate and calcium absorption in the rat in vivo. The reported results indicate that proteins and/or enzymes with a rapid turn-over are involved in the mechanism of phosphate intestinal absorption, and confirm previous observations that phosphate and calcium are transported across the intestine by different mechanisms.