The Intricacies of Renal Phosphate Reabsorption—An Overview

Abstract

To maintain an optimal body content of phosphorus throughout postnatal life, variable phosphate absorption from food must be finely matched with urinary excretion. This amazing feat is accomplished through synchronised phosphate transport by myriads of ciliated cells lining the renal proximal tubules. These respond in real time to changes in phosphate and composition of the renal filtrate and to hormonal instructions. How they do this has stimulated decades of research. New analytical techniques, coupled with incredible advances in computer technology, have opened new avenues for investigation at a sub-cellular level. There has been a surge of research into different aspects of the process. These have verified long-held beliefs and are also dramatically extending our vision of the intense, integrated, intracellular activity which mediates phosphate absorption. Already, some have indicated new approaches for pharmacological intervention to regulate phosphate in common conditions, including chronic renal failure and osteoporosis, as well as rare inherited biochemical disorders. It is a rapidly evolving field. The aim here is to provide an overview of our current knowledge, to show where it is leading, and where there are uncertainties. Hopefully, this will raise questions and stimulate new ideas for further research.

Keywords

• regulator of G protein signalling 14 (RGS14)
• fibroblast growth factor 23 (FGF23)
• parathyroid hormone/parathyroid hormone related protein receptor (PTH/PTHrP receptor)
• Na⁺/H⁺ exchange regulatory cofactor-1 (NHERF1)
• NaPi-2a sodium-dependent phosphate transporter-2a (NaPi-2a)
• kidney stones