Electrochemical forces for chloride transport in the proximal tubules of the rat kidney

Abstract

The electrochemical forces for Cl transport in the proximal tubule of the rat kidney were studied using micropuncture techniques. Electrical transmembrane potentials were recorded in randomly punctured tubules with Ling-Gerhard electrodes. Cl activities in the luminal, cellular and interstitial compartments were measured with ion selective micro-electrodes. Electrical potential measurements between cell to interstitium and lumen to interstitium were -72.1 .+-. 2.6 mV and + 0.5 .+-. 1.4 mV (mean .+-. SD), respectively. The calculated Cl concentrations for lumen, cell and interstitium were 133.0 .+-. mM, 8.5 .+-. 1.0 mM and 99.1 .+-. 3.2 mM (mean .+-. SD), respectively. The net electrochemical forces, qualitatively, offer a passive Cl ion pathway through the tubular wall and a Cl equilibrium over the luminal membrane seems to exist.