A COMPARISON OF THE ELECTRICAL RESISTANCES OF THE SURFACE CELL MEMBRANE AND CELLULAR WALL IN THE PROXIMAL TUBULE OF THE NEWT KIDNEY

Abstract

The elec-trical properties of the proximal tubular cells were studied in the newt kidney using microelectrode techniques. The surface membrane of the tubular cells behaved like a simple resistor when a minute current was applied intracellularly. The changes in the transmembrane potential was linearly proportional to the strength of applied current and there was neither the rectification nor the self-generative response within a wide range of current strength. The potential change caused by the intracellular application of current spread over considerable distances along the longitudinal axis of the tubule. The tubular wall, thus, behaved like a core conductor. Application of the simple core conductor theory to the model of the tubular wall gave the values of 400u for the space constant, 3.1 x 105X1 for the effective resistance, 836X2 cm2 for the specific resistance of the surface membrane and 625ft cm for the specific resistance of the core (cytoplasm including intercellular membranes). A comparison of the surface membrane resistance to the transtubular resistance suggests that there are significant extracellular shunt paths for electrolytes within the tubular wall. The leaky nature of the proximal segment was ascribed to the presence of such shunt paths.