Determination of the Ionic Exchange during Nervous Activity by Activation Analysis

Abstract

EXPERIMENTS on the sodium and potassium content of cells, and on the part played by these ions in nervous conduction, have often been hampered by the inconvenience and insensitivity of conventional methods for the estimation of the alkali metals. The advent of radioactive isotopes has given a new impetus to such studies; but the necessity for knowing the intracellular ionic concentrations remains. In working with isolated nerve axons, for example, although the inward ionic fluxes can be measured directly with potassium-42 and sodium-24, the outward fluxes can only be found by observing the time-course of loss of radioactive ions in an inactive solution, and their absolute values can only be calculated if the true ionic content of the axoplasm is known^1,2.