Intracellular Chloride Activity of Crayfish Giant Axons

Abstract

RECENT measurements of chloride concentrations in the squid giant nerve axon have indicated that intracellular chloride ion is of higher concentration than would be expected if chloride ions were distributed across the cell membrane in equilibrium with the transmembrane potential¹. Measurements of intracellular chloride activity of squid giant axons with an Ag–AgCl electrode have also indicated higher intracellular chloride activities than could be accounted for from equilibrium considerations². Similarly, it has also been found in smooth muscle that intracellular chloride is of higher concentration than expected^3,4. In this communication, experiments are described which indicate that the intracellular chloride activity of crayfish giant axons (Procambarus clarkii) is higher than that expected from considerations based on chloride being distributed in equilibrium with the membrane potential. These experimental results are based on chloride activity measurements made with an intracellular Ag–AgCl electrode.