Mechanism of Absorption of Inorganic Phosphate from Blood by Tissue Cells

Abstract

IN the course of a study of the phosphorus metabolism of liver, evidence was obtained suggesting that the absorption of inorganic phosphate ions from the blood is not a simple exchange of ions across the cell membrane but that it requires an energy-yielding phosphorylating mechanism. Accordingly, this hypothesis was tested by experiments in which rabbit liver left in situ was perfused with homologous plasma to which a small amount of carrier-free inorganic ³²PO₄³⁻ was added (2–5 µc. per litre) with or without 0.01 M sodium azide. The heparinized plasma, after addition of phosphorus-32 in saline, was divided into two equal volumes to one of which sodium azide was added; the two lots were used for the control and experimental perfusions, which were carried out on the liver of litter-mate animals.