The effect of crown ethers on ionic currents in myelinated nerve fibres from Xenopus laevis

The effect of several crown ethers on the currents at the node of Ranvier was studied. At differing potencies they caused a time- and potential-dependent inactivation of potassium permeability and a time- and potential-independent decrease in sodium permeability. The relative effect on potassium and sodium systems varied and was not directly related to their ionophoric properties. A computer analysis indicated that the induced inactivation was dependent on the normal potassium activation mechanism.