Tetraethylammonium Ions: Effect of Presynaptic Injection on Synaptic Transmission

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Science  10 Mar 1967:
Vol. 155, Issue 3767, pp. 1257-1259
DOI: 10.1126/science.155.3767.1257


Tetraethylammonium ions were injected into the presynaptic axon of the squid giant synapse. Injection of these ions caused prolongation of the action potential with decreased out ward current. The prolonged spike was associated with increased release and prolonged activity of the transmitter substance. Although the amplitude of the postsynaptic potential increased with presynaptic depolarization, strong depolarization blocked transmitter re lease. In the injected presynaptic axon, transmitter release was blocked by 10—6 gram of tetrodotoxin per milliliter. Transmitter release appears to be under control of presynaptic potential levels.