Evidence for the formation of functionally distinct αβγε GABA A receptors

作者：Paul A Davies, Ewen F. Kirkness, Tim G. Hales · 发表于：The Journal of Physiology · 年份：2001 · DOI：10.1111/j.1469-7793.2001.0101k.x · 被引用次数：39 · 研究领域：Neuroscience and Neuropharmacology Research、Neuroscience and Neural Engineering、Photoreceptor and optogenetics research

1. We transiently introduced the human GABA(A) receptor epsilon subunit cDNA into a human embryonic kidney (HEK) cell line stably expressing alpha1beta3gamma2 receptors (WSS-1 cells) to establish whether the subunit competes with the gamma2 subunit for assembly into receptors. GABA-evoked currents were recorded using the patch-clamp technique from cells transfected with cDNA encoding green fluorescent protein (GFP) alone or in combination with the epsilon subunit cDNA. 2. The epsilon subunit did not change the potency of GABA: the GABA EC(50) was 34 +/- 6 microM in control WSS-1 cells and 37 +/- 6 microM in cells expressing the epsilon subunit. The introduction of the epsilon subunit reduced the peak current amplitude activated by GABA (1 mM) from 1.8 +/- 0.2 nA in control cells to 0.9 +/- 0.2 nA in cells expressing the epsilon subunit (P < 0.05). 3. The epsilon subunit caused the appearance of leak currents recorded in the absence of GABA. Outside-out patches excised from epsilon subunit-containing WSS-1 cells exhibited spontaneously opening GABA(A) channels not seen in patches excised from control GFP-expressing WSS-1 cells. Introduction of the epsilon subunit did not alter the GABA-evoked single-channel cord conductance. 4. The anaesthetic 2,6-diisopropylphenol (propofol, 3 microM) and the benzodiazepine flunitrazepam (1 microM) potentiated GABA-evoked currents recorded from control cells labelled with GFP. The epsilon subunit reduced potentiation by both agents 48-96 h af...