Electrochemical potentials of chloride in proximal renal tubule of Necturus maculosus

Abstract

1. 1. Electrometric analysis employing double-barrelled Cl −-selective liquid ion-exchange microelectrodes yielded a mean intracellular [Cl −] of 18·7 ± 1·3 mM in single renal cells of Necturus maculosus proximal tubule. Thus two-thirds of the total intracellular Cl − content is electrometrically active. 2. 2. Thus intracellular Cl − ion is at a higher electrochemical potential than Cl − in either the luminal or peritubular phase. 3. 3. If CI − reabsorption across the proximal tubular epithelium consists of ion transport across two individual cell membranes in series, then the first reabsorptive step across the luminal cell membrane must be active while the second step across the peritubular membrane is passive.