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Conductance of GABA A Channels Activated by Pentobarbitone in Hippocampal Neurons from Newborn Rats
Author(s) -
Eghbali Mansoureh,
Birnir Bryndis,
Gage Peter W.
Publication year - 2003
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2003.047415
Subject(s) - hippocampal formation , conductance , neuroscience , bicuculline , hippocampus , electrophysiology , chemistry , anesthesia , biophysics , medicine , psychology , biology , physics , gabaa receptor , receptor , condensed matter physics
Neurons were obtained from the CA1 region of the hippocampus of newborn rats and maintained in culture. Channels were activated by pentobarbitone in cell‐attached, inside‐out or outside‐out patches, normally by applying pentobarbitone in flowing bath solution. Currents were outwardly rectifying and blocked by bicuculline, properties of GABA A channels in these cells. Maximum channel conductance increased as pentobarbitone concentration was increased to 500 μ m but conductance then decreased as pentobarbitone concentration was raised further. The best fit of a Hill‐type equation to the relationship between maximum channel conductance and pentobarbitone concentration (up to 500 μ m ) gave an EC 50 of 41 μ m , a maximum conductance of 36 pS and a Hill coefficient of 1.6. Bicuculline decreased the maximum conductance of the channels activated by pentobarbitone, with an IC 50 of 224 μ m . Diazepam increased channel conductance, with a maximum effect being obtained with 1 μ M diazepam. Diazepam (1 μ M ) decreased the EC 50 of the pentobarbitone effect on channel conductance from 41 μ M to 7.2 μ M and increased maximum conductance to 72 pS. We conclude that GABA A channel conductance is related to the concentration of the allosteric agonist pentobarbitone.