Phosphaturic response of hydrocortisone in the presence and the absence of parathyroid hormone

The effect of hydrocortisone (HC) on the renal Pi transport in the presence and in the absence of parathyroid hormone (PTH) in the rat was examined using clearance techniques. During constant infusion of PTH in parathyroidectomized (PTX) rats, HC decreased the reabsorption of Pi from 2.84 to 2.33 mol/min (P<0.001), the Tm_Pi from 4.55 to 3.83 mol/min (P<0.001), the reabs. Pi/GFR values from 0.93 to 0.74 (P<0.001) and the Tm_Pi/GFR from 1.73 to 1.42 mol/ml (P<0.001). In the absence of PTH, HC diminished the Tm_Pi from 8.36 to 6.58 mol/min (P<0.005) and the Tm_Pi/GFR from 3.36 to 2.51 mol/ml (P<0.001). It is concluded that the phosphaturic response of hydrocortisone may be important in the homeostasis of inorganic phosphate in the body.This work was supported by a grant from the Deutsche Forschungsgemeinschaft (Fr 239/8)