Blockage of Sodium Conductance Increase in Lobster Giant Axon by Tarichatoxin (Tetrodotoxin) |
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| Authors: | M Takata J W Moore C Y Kao and F A Fuhrman |
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| Institution: | From the Department of Physiology and Pharmacology, Duke University Medical Center, Durham, North Carolina, the Department of Pharmacology, State University of New York, Downstate Medical Center, Brooklyn, New York, and the Fleischmann Laboratories, Stanford University Medical Center, Palo Alto, California. |
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| Abstract: | Tarichatoxin, isolated from California newt eggs, has been found to selectively block the increase of sodium conductance associated with excitation in lobster giant axons at nanomolar concentrations. This resulted from a reduction in the amplitude of the conductance increase rather than a change in its temporal characteristics. The normal potassium conductance increase with depolarization is not altered. A high concentration of calcium applied concomitantly with the toxin significantly improves the reversibility of the sodium blocking. This toxin has recently been identified as chemically identical with tetrodotoxin from the puffer fish. Toxins from the two sources are equally effective and are shown to have an action which is distinctly different from that of procaine. |
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