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Dendrotoxin and charybdotoxin increase the cytosolic concentration of free Ca 2+ in cerebrocortical synaptosomes: An effect not shared by apamin
Author(s) -
Tibbs Gareth R.,
Nicholls David G.,
Dolly J.Oliver
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)81081-6
Subject(s) - charybdotoxin , apamin , chemistry , biophysics , biochemistry , membrane potential , potassium channel , biology
Nanomolar concentrations of charybdotoxin or dendrotoxin increase the cytoplasmic free Ca 2+ concentration in isolated central nerve terminals. The effects of the two toxins, normally considered to be blockers of K + channels controlled by voltage in a Ca 2+ ‐sensitive or ‐insensitive manner, respectively, show only marginal additivity. Apamin, an inhibitor of low conductance Ca 2+ ‐activated K + channels, was without effect in either the absence or presence of dendrotoxin. The effect of charybdotoxin on polarized, isolated central nerve terminals seems to be mediated largely by a block of K + channels sensitive to dendrotoxin. Apparently, these voltage‐operated K + channels make a more significant contribution to maintaining the polarized potential of synaptosomes than do those activated by Ca 2+ .