Abstract

Two renal proximal tubular apical sodium-dependent transport systems for phosphate (Na/Pi cotransporter) have been identified. Recent studies demonstrated that the abundance of the type II Na/Pi cotransporter in the brush border is critical for the capacity of phosphate reabsorption. Evidence was obtained that a change of apical Na/Pi cotransporters may occur via endo/ exocytic processes and via protein-synthesis-dependent mechanisms involving altered transcription and/or stability of mRNA. In addition, acute control of apical Na/Pi cotransport may occur via the pH dependence and electrogenicity of the Na/Pi cotransporter.