Use of Potassium Ion-Exchanger Electrode for Microanalysis

Abstract

Numerous constituents of renal tubule fluid have been measured in vitro after collecting small volumes in micropipets. Some of these (hydrogen, sodium, and potassium ions) have also been measured in vivo by direct puncture of surface tubules with micro-electrodes (1–6). Similarly the intracellular ionic composition of renal tubule cells has been estimated chemically in digests of renal tissue by several workers (7–9) and, recently, some results of direct measurements with potassium sensitive electrodes have been reported (6,9). Knowledge of cellular and luminal potassium concentrations in mammalian renal tubules, especially in the distal portion of the nephron, is crucial to an understanding of the mechanisms by which potassium is transported and electrical potentials are generated. In the course of attempting in vivo measurements of intracellular and intratubular potassium activity we have been confronted by the special problems attending measurements in the mammalian distal tubule.