Water Flux and Electrokinetic Phenomena in the Squid Axon

The fact that the nerve m e m b r a n e shows permselectivity for cations (1) suggests the presence of fixed negative charges in its matrix. Ionic exchange membranes show some other characteristic propeties besides permselectivity. Among them are the electrical p h e n o m e n a produced by water flow across the m e m b r a n e as well as the movemen t of water caused by the passage of current . These are the so-called electrokinetic phenomena (2). Research on these phenomena in the nerve m e m b r a n e should give us informat ion about the sign and density of its fixed charge. Therefore experiments have been designed for a study of water flow a nd a measurement of s t reaming potentials and currents across the axon membrane .