EFFECTS OF TETRAETHYLAMMONIUM CHLORIDE ON ELECTRICAL ACTIVITIES OF FROG SYMPATHETIC GANGLION CELLS

¹ Department of Physiology, University of Utah College of Medicine, Salt Lake City, Utah

Transmembrane resting and action potentials were recorded, in vitro, in frog sympathetic ganglion cells during exposure to tetraethylammonium (TEA). In TEA action potentials were prolonged, with plateaus; thresholds for direct stiumlation were reduced; and rhythmic spontaneous discharge developed. TEA-prolonged action potentials exhibited greater "overshoot" and less "undershoot" of the resting potentials, which were unchanged.

Polarizing currents in conjunction with, or preceding, plateaued action potentials modified their duration. Inward currents decreased, and outward currents increased, plateau duration in a graded manner. Following tetanic stimulation plateau duration was decreased, but recovered to control duration with time.

The results are discussed in reference to previous studies with TEA in other tissues. Note is made of possible mechanisms involved in the formation of plateaued action potentials and their premature termination by inward currents. The nature of the effects of polarizing currents in this study leads to the hypothesis: TEA may act by occupying membrane sites normally available to calcium.