Effect of cortisone on jejunal phosphate absorption in hypophysectomized rats

The effect of cortisone on jejunal active and passive phosphate transport was evaluated by the in situ intestinal loop technique using 1.2 and 50 mM concentrations of phosphate. Animals were divided into four groups: (1) intact, (2) hypophysectomized (HX), (3) HX plus cortisone, (4) HX plus 1,25-dihydroxyvitamin D3[1,25(OH)2D3]. The results of the experiment suggest that cortisone enhances jejunal phosphate absorption in HX rats through two mechanisms: (1) increased mucosal cell membrane permeability, (2) enhanced water movement, resulting in a rise of luminal phosphate concentration which favors the active and passive transport of phosphate. Stimulation of phosphate transport by cortisone is different from the unidirectional specific phosphate transport caused by 1,25(OH)2D3.