Characterization of the gamma-aminobutyric acidA receptor-channel complex composed of alpha 1 beta 2 and alpha 1 beta 3 subunits from rat brain.
The cloned alpha 1, beta 2 and beta 3 subunits of the gamma-aminobutyric acid (GABA)A receptor-channel complex from rat brain were coexpressed as alpha beta complexes in cultured Chinese hamster ovary cells. Electrophysiological characterization of alpha 1 beta 2 and alpha 1 beta 3 receptor subunit arrangements was performed utilizing patch electrodes in the whole-cell recording configuration. The reversal potential of the current activated by either GABA or muscimol corresponded to that expected for Cl- ions and was dependent on the Cl- gradient. The dose response to GABA for activation of Cl- currents by either subunit combination displayed similar potencies. Currents were partially blocked by the reversible antagonist bicuculline. (-)Pentobarbital was ineffective by itself, but potentiated responses to GABA. The steroid alphaxalone (3 alpha-hydroxy 5 alpha-pregnane 11,20-dione) produced just-detectable inward currents, but did not potentiate GABA-activated currents. Diazepam was completely ineffective. The kinetics and conductance of the Cl- ion channels were inferred from spectral analysis of agonist-induced current fluctuations. Both kinetics and conductance were dependent on agonist structure.
Laboratory of Neurophysiology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland.
A Y
AY
Valeyev
J L
JL
Barker
R A
RA
Cruciani
G D
GD
Lange
V V
VV
Smallwood
L C
LC
Mahan
D000818:Animals; D001921:Brain / Q000378:metabolism*; D016466:CHO Cells; D002712:Chlorides / Q000378:metabolism; D006224:Cricetinae; D003975:Diazepam / Q000494:pharmacology; D008564:Membrane Potentials; D010424:Pentobarbital / Q000494:pharmacology; D011277:Pregnanediones / Q000494:pharmacology; D051381:Rats; D011963:Receptors, GABA-A / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D002712:Chlorides; D011277:Pregnanediones; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; C006477:alphaxalone; D010424:Pentobarbital; D003975:Diazepam