EFFECT OF ALKALI-EARTH CATIONS ON FROG SPINAL GANGLION CELL

Abstract

The effect of alkali-earth cations on the membrane potential of isolated toad spinal ganglion cells was studied. In Ba solution, the initial membrane hyperpolarization was followed by a progressive depolarization to a critical potential level from where a prolonged action potential was spontaneously initiated. The analysis of the changes in the resting and action potentials led to the conclusion that Ba ions can exert a dual action on the membrane; e.g., a Ca-like action, namely, binding with the membrane and controlling the membrane permeability or potential, and a Na-like action, namely, acting as a charge carrier by penetrating the membrane. It was suggested that other alkali-earth cations, such as Ca, Mg and Sr, can also exert such a dual action on particular kinds of membranes; the affinity of the membrane lipoprotein to a given alkali-earth cation determines the mode of action of this particular ion.