Molecular modulation of recombinant rat alpha1beta2gamma2 GABA(A) receptor channels by diazepam.
Recombinant gamma-aminobutyric acid (GABA(A)) receptor channels containing alpha1beta2gamma2-subunits were transiently expressed in HEK293 cells. Modulation by diazepam (DZ) was investigated using the patch-clamp technique with a device for ultra-fast solution exchange. GABA activated Cl(-)-currents were potentiated when DZ > 0.1 microM was added to non-saturating concentrations of GABA (< 0.1 mM GABA). Maximal potentiation of the peak current amplitude by a factor of 2.5 was observed when 1 microM DZ was added to the test-solution. Deactivation of GABA-activated currents after the end of GABA pulses was best fitted with two time constants. After application of DZ + GABA, increase of time constants of deactivation was measured. It was independent on GABA concentration. We conclude that prolongation of deactivation after application of GABA + DZ may be an important mechanism of the modulatory action of DZ at GABA(A) receptor channels.
Krampfl
K
K
Department of Neurology, Technical University Munich, Germany.
Lepier
A
A
Jahn
K
K
Franke
C
C
Bufler
J
J
D000818:Animals; D002460:Cell Line; D003975:Diazepam / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D051381:Rats; D011963:Receptors, GABA-A / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000187:drug effects / Q000235:genetics; D013997:Time Factors; D014162:Transfection; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D011963:Receptors, GABA-A; D011994:Recombinant Proteins; D005680:gamma-Aminobutyric Acid; D003975:Diazepam