Electrical properties of the smooth muscle membrane of the guinea‐pig vas deferens

Abstract

The effects of polarizing current on single smooth muscle cells of the isolated guinea-pig vas deferens have been studied by means of a bridge circuit in which the same electrode was used to pass current and record membrane potential. Most cells had polarization resistances from 15 to 37 M[OMEGA]. Depolarizing currents caused graded spikes up to a maximum amplitude of 75 mV. Self-regenerative spikes occurred in some cells if the membrane was depolarized by > 35 mV. Currents of long duration and sufficient intensify caused a repetitive discharge. Spikes arising from excitatory junction potentials were always "all-or-none" in contrast to the graded responses to intra-cellular stimulation. Electrotonic potentials declined much more rapidly than spontaneous excitatory junction potentials?(EJPs); thus the time course of the EJP cannot be determined by the passive electrical properties of the smooth muscle cell membrane.