Electrical interactions between normal and TEA-treated zones of squid axon

¹ Laboratory of Neurophysiology, Institute of Neurological Diseases and Blindness, National Institutes of Health, Bethesda, Maryland

By stepwise injection of tetraethylammonium (TEA) chloride into a squid giant axon, it was shown that the degree of prolongation of the action potential by TEA depends on the length of the TEA-treated zone of the axon. Near the boundary between normal and TEA-treated zones of the axon, oscillatory potentials were often observed during the plateau of the prolonged action potential. It was shown that repetitive firing of impulses at the boundary originated in the TEA-treated zone, not in the normal zone. At the boundary between normal and TEA-treated zones, where the concentration of TEA changed continuously, there was a discontinuous change in duration of the action potential, indicating the existence of a sharp delineation between the zones developing long and short responses. Propagation of abolition of an action potential was demonstrated in uniformly TEA-treated axons.