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The actions of a red tide toxin from Ptychodiscus brevis on single sodium channels in mammalian neuroblastoma cells
Author(s) -
Sheridan Robert E.,
Adler Michael
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81389-4
Subject(s) - sodium channel , depolarization , biophysics , chemistry , sodium , membrane potential , conductance , toxin , biochemistry , biology , mathematics , organic chemistry , combinatorics
The actions of brevetoxin (PbTX‐3) were studied on single, voltage‐dependent sodium channels and whole‐cell currents from the neuroblastoma × glioma cell line NG108‐15. Purified PbTX‐3 shifted the activation of sodium channels to membrane potentials negative to normal. PbTX‐3 did not alter the single‐channel mean open lifetime, suggesting that the toxin does not change the rate of sodium channel inactivation from the open state. There was also no change in single‐channel conductance. These results indicate that brevetoxin increases sodium current at rest by shifting the voltage dependence of channel activation and that the resulting depolarization is limited by channel inactivation.