THE PARATHYROIDS AND THE INTESTINAL ABSORPTION OF CALCIUM, STRONTIUM AND PHOSPHATE IONS IN THE RAT1

Abstract

The effect of parathyroidectomy (PTX) on the intestinal absorption of calcium, strontium and phosphate ions was investigated in vivo and in vitro in the rat. At either 5 or 24 hours after parathyroidectomy, the plasma calcium was significantly decreased in comparison to the controls (mock operated) which indicated the success of the operation. It was observed that PTX did not alter the degree of absorption of Ca⁴⁵, Sr⁸⁵ or P³² by rat duodenum and ileum in vivo. In rats raised on a high calcium diet, there was an apparent slight decrease in deposition of Ca⁴⁵ and Sr⁸⁵ in the femur; in rats given a low calcium diet for two weeks, PTX did not influence femur deposition of alkaline earths in respect to the controls. In vitro studies with isolated everted gut segments indicated that the transfer of Ca⁴⁵ and Sr⁸⁵ across the duodenum and ileum was not influenced by the parathyroid status of the donor rat.