Action of Iontophoretically Applied Tetrodotoxin on Cortical Nerve Cells

TETRODOTOXIN is the potent poison found in puffer fish of the sub-order Gymnodontes and newts of the genus Taricha1. In low concentrations, tetrodotoxin suppresses action potentials in a variety of excitable tissues including frog myelinated nerve fibres, frog muscle fibres2, lobster and squid giant axons3,4 and cardiac muscle5. The action potentials of some other tissues, such as crustacean muscle fibres, the taenia coli and vas deferens of guinea-pigs are not affected by tetrodotoxin6–8. Although evoked potentials in the cerebral cortex are depressed by topically applied tetrodotoxin9, its effect on action potentials of nerve cells in the central nervous system has not been demonstrated.