Premium
Pharmacological and Electrophysiological Properties of Recombinant GABA A Receptors Comprising the α3, β1 and γ2 Subunits
Author(s) -
Knoflach F.,
Backus K. H.,
Giller T.,
Malherbe P.,
Pflimlin P.,
Möhler H.,
Trube G.
Publication year - 1992
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1992.tb00103.x
Subject(s) - gabaa receptor , picrotoxin , gabaa rho receptor , patch clamp , bicuculline , gaba receptor antagonist , flumazenil , flunitrazepam , chemistry , receptor , protein subunit , transfection , voltage clamp , biophysics , pharmacology , microbiology and biotechnology , biology , biochemistry , membrane potential , gene
To assess the role of subunits for channel function and drug modulation in recombinant GABA A receptors, the α3β1γ2 subunits and the dual combinations α3β1, β1γ2 and α3γ2 were expressed by transfection of human embryonic kidney cells and by RNA injection in Xenopus oocytes (α3β1γ2 combination). GABA‐induced chloride currents were recorded using the whole‐cell configuration of the patch‐clamp technique (transfected cells) or the voltage‐clamp technique (oocytes). The currents recorded from the α3β1Γ2 subunit combination in transfected cells were reduced by bicuculline and picrotoxin, enhanced by flunitrazepam in a flumazenil‐sensitive manner and reduced by β‐carboline‐3‐carboxylic acid methyl ester (β‐CCM). The GABA‐induced current was reduced by β‐CCM in all combinations containing the γ2 subunit, but potentiation by flunitrazepam was only obtained when the 72 subunit was coexpressed in the presence of the α3 subunit (α3β1γ2 or α3γ2). The GABA sensitivities of the receptors were similar when the α3β1γ2 combination was expressed in oocytes (half‐maximum effective concentration = 240 μM) or in the kidney cell line (270 μM). However, the currents were less potentiated by flunitrazepam in oocytes (129% of controls) than in transfected cells (189%). These results suggest that the α3β1γ2 subunit combination, which is coexpressed in various brain regions as shown by in situ hybridization histochemistry, may represent a building block of functional GABA A receptors in situ.