Mechanism of Renal Tubular Phosphate Reabsorption and the Influence Thereon of Vitamin D in Completely Parathyroidectomized Rats

Publisher Website
Google Scholar
Abstract
This paper presents studies designed to reveal whether, under conditions of constant parathyroid and vit. D status, there is a renal tubular transfer maximum for inorganic phosphate or, alternatively, a tendency for the tubules to reabsorb a constant fraction of the phosphate filtered by the glomeruli. For this purpose groups of rats with authenticated aparathyroidism were subjected to varying phosphate loads at each of 3 levels of vit D intake, 100, 10,000 and 100,000 I. U./day. The results obtained were found to be incompatible with the former, but closely in keeping with the latter thesis over a wide range of glomerular filtrate phosphate loads. In addition these studies show that in totally aparathyroid animals, an increase in vit. D dosage causes the tubules to reabsorb a smaller percentage of the glomerular filtrate phosphate. This action is qualitatively similar to that observed previously for parathyroid hormone.