Effects of the propagation velocity of a surface depolarization wave on the extracellular potential of an excitable cell

Extracellular electric fields have been proposed as a mechanism for electrical coupling between excitable cells. This study deals with the extracellular potential produced by an isolated excitable spherical cell due to a traveling depolarization wave on the cell´s surface. Both uniform and nonuniform propagation velocity profiles are considered. Using boundary element methods, the extracellular potential was computed. The polarity of the extracellular potential was found to be space-dependent. The peak extracellular potential increased when a) the propagation velocity decreased, b) the rise time of the depolarization decreased, and c) the extracellular resistivity increased.