A study of renal phosphate excretion in the dog

Abstract

Experiments were performed in 25 dogs in an attempt to demonstrate renal tubular secretion of inorganic phosphate. Clearances were obtained as plasma concentrations of phosphate were varied from normal to as high as 20 µm/ml. In addition, several manipulations were employed in various combinations with the presumption that they would facilitate the demonstration of secretion. The manipulations were the infusion of glucose, infusion of p-aminohippurate, administration of parathyroid extract, mannitol diuresis, loading with sodium phosphate intravenously for 3 days prior to study, and reduction of glomerular filtration rate. Despite the manipulations, no evidence of net secretion was obtained. The estimated filtered load of phosphate exceeded the rate of excretion of phosphate in every experiment. Furthermore, review of the literature indicates that secretion of phosphate in mammalian species has not been clearly established.