A Small Analog Computer for Continuous Measurement of Intracellular Ion Activities

The operation of liquid ion exchanger microelectrodes that allows measurement of internal potassium and chloride activities in identifiable neurons has been described. A computer that solves the logarithmic equation necessary for computation of these activities has been constructed and tested successfully. The great value of the computer is that it permits continuous measurement of these activities. When the internal ion activities change, such continuous measurement allows calculation of potassium and chloride permeabilities in single neurons.