The Acute Effect of 25-Hydroxycholecalciferol on Renal Handling of Phosphorus: EVIDENCE FOR A PARATHYROID HORMONE-DEPENDENT MECHANISM

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Abstract

The acute effect of i.v. and direct intrarenal arterial infusion of 25-hydroxycholecalciferol (25HCC) and 1,25-dihydroxycholecalciferol (1,25-DHCC) on renal handling of phosphorus was evaluated in the following groups of rats: (a) intact animals, (b) parathyroidectomized (PTX) hypocalcemic rats, (c) PTX rats in which normocalcemia was maintained with calcium supplements and (d) PTX animals in which urinary phosphorus was augmented by (i) i.v. sodium phosphate, (ii) expansion of the extracellular fluid volume with normal saline, and (iii) i.v. parathyroid hormone (PTH). Clearances of inulin (CIn), phosphorus (CP), and fractional clearances of phosphorus (CP/CIn) of the experimental groups were compared with those of the corresponding control groups, and the clearances of the infused kidneys with those of the contralateral kidneys.

Authors

Mordecai M. Popovtzer, John B. Robinette, Hector F. Deluca, Michael F. Holick