Intracellular conductance of aplysia neurons and squid axon as determined by a new technique

A metal microelectrode can be used to record the conductivity of intracellular fluid in small volumes. The equivalent capacitance recorded from such an electrode, when subjected to alternating current at 100 kHz, varies linearly with the conductance of the solution in contact with the electrode tip. The conductance of the interior of Aplysia neurons is less than 10% that of sea water, whereas the conductance of squid axoplasm is approximately equal to that of sea water. These results suggest that there is extensive binding of water and small ions in Aplysia neurons but not in squid axoplasm.