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Convulsant doses of penicillin shorten the lifetime of GABA‐induced channels in cultured central neurones
Author(s) -
Chow Phoebe,
Mathers David
Publication year - 1986
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.1476-5381.1986.tb10234.x
Subject(s) - convulsant , patch clamp , chemistry , biophysics , gamma aminobutyric acid , extracellular , membrane potential , electrophysiology , sodium channel , pharmacology , biochemistry , sodium , neuroscience , biology , receptor , organic chemistry
1 The influence of sodium benzylpenicillin (PCN) on membrane channels activated by γ‐aminobutyric acid (GABA) was studied in cultured spinal neurones of the mouse by the extracellular patch clamp technique. 2 In whole‐cell, current clamp recordings, concentrations of PCN above 0.2 mM significantly reduced the amplitude of the GABA response. 3 Single channel currents activated by GABA were studied in outside‐out patches of neuronal membrane. In both the absence and presence of PCN, cumulative open time distributions for GABA‐activated channels were well fitted by the sum of two exponential terms, characterized by fast (τ f ) and slow time constants (τ s ). 4 PCN (2 mM) reduced the mean value of τ s from 4.29 ± 0.56 ms (mean ± s.e.mean) to 1.12 ± 0.09 ms but had no significant effect on τ f . 5 The mean open time of GABA‐activated channels, calculated from the double exponential fits, decreased from 1.39 ± 0.35 ms to 0.53 ± 0.02 ms in the presence of 2 mM PCN. 6 The reduced mean open time of GABA‐sensitive channels seen in the presence of PCN may contribute to the convulsant action of the drug in vivo.