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Pharmacology of the Ca 2+ ‐dependent K + channel in corn protoplasts
Author(s) -
Karen A. Ketchum,
Ronald J. Poole
Publication year - 1990
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(90)81343-m
Subject(s) - charybdotoxin , apamin , chemistry , potassium channel , channel blocker , biophysics , potassium channel blocker , potassium , membrane potential , biochemistry , calcium , biology , organic chemistry
We investigated the sensitivity of the Ca 2+ ‐dependent K + current, I K (Ca) , present in corn protoplasts, to different K + channel blockers. I K(Ca) was inhibited by external Cs + (10 mM), Ba 2+ (10 mM), and quinine (0.5 mM): reagents which block many types of outward‐rectifying K + channels. In contrast 4‐aminopyridine (5 mM), an inhibitor of delayed rectifier or inactivating K + currents, had no effect. Neither of the peptide toxins, apamin or charybdotoxin, specific for Ca 2+ ‐dependent K + channels in animal cells, inhibited currents when used in the nanomolar concentration range. However, higher levels of charybdotoxin (10 μM) caused marked reduction of I K(Ca) .