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The mechanism of steroid anaesthetic (alphaxalone) block of acetylcholine‐induced ionic currents
Author(s) -
Gillo Boaz,
Lass Yoram
Publication year - 1984
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1984.tb16474.x
Subject(s) - acetylcholine , chemistry , conductance , ionic bonding , blockade , ed50 , electrophysiology , anesthesia , biophysics , pharmacology , medicine , ion , biochemistry , mathematics , biology , receptor , organic chemistry , combinatorics , in vitro
1 The effects of the steroid anaesthetic alphaxalone on acetylcholine (ACh)‐induced ionic channels were studied in voltage clamped ‘myoballs’ in culture. 2 Alphaxalone produced a reversible blockade of the ACh‐evoked inward current, ED 50 = 6.0 μ M . 3 The ACh reversal potential (−5.0 mV), the single channel conductance (13.5 pS) and mean open time (3.6 ms) were unchanged by the drug. Thus, alphaxalone produced an ‘all or none’ block of the ionic channel. 4 In double pulse conditioning experiments, alphaxalone produced an additional inhibition with a time constant of recovery (550 ms) much longer than the time constant of recovery of the normal desensitization (250 ms). 5 It was concluded that alphaxalone blocks active (open) ionic channels.