A method for measuring resting and action potentials with external electrodes in crayfish giant axons

Abstract

The true resting membrane potential and membrane action potential of crayfish giant axons were recorded with two external electrodes using a partition method in which the insulation grade was extensively improved by utilizing a water-absorbing particle mixed with vaseline and liquid paraffin, and the residual membrane potential at the lateral reference pool was removed by using an offset solution. The offset solution contained 10-4M of ouabain to block electrogenic sodium pump and a higher potassium concentration than that of the isotonic KCl solution. No short circuiting correction was necessary within an error of a few percent. Elimination of chloride ions from the offset solution substantially prolonged the surviving time of the preparation. This experimental system was developed to study a cell in as intact condition as possible, especially in a long-term experiment.