Electrophysiological studies of the cell membrane of bullfrog sympathetic neurons.

Active and passive properties of dissociated bullfrog sympathetic ganglion cells were examined in the whole-cell configuration. Electrical constants were 107 k omega cm2 and 1 microFcm2 for the unitary cell membrane area. Under conditions in which the equilibrium potential was 55 mV for sodium ions and -101 mV for potassium ions, the action potential and its after-hyperpolarization peaked at 50 and -83 mV, respectively, when elicited from the resting potential of -63 mV. These observations are consistent with those reported previously for other autonomic neurons. The reversal potential of the after-hyperpolarization was approximately 10 mV less negative than the potassium equilibrium potential. The basis of this difference has been discussed using a hypothetical equivalent circuit.