Spontaneously Opening GABAA Channels in CA1 Pyramidal Neurones of Rat Hippocampus |
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Authors: | B Birnir AB Everitt MSF Lim PW Gage |
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Institution: | (1) Membrane Biology Program, John Curtin School of Medical Research, Australian National University, Canberra, ACT 2601, Australia, AU |
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Abstract: | Spontaneous, single channel, chloride currents were recorded in 48% of cell-attached patches on neurones in the CA1 region
of rat hippocampal slices. In some patches, there was more than 1 channel active. They showed outward rectification: both
channel conductance and open probability were greater at depolarized than at hyperpolarized potentials. Channels activated
by γ-aminobutyric acid (GABA) in silent patches on the same neurones had similar conductance and outward rectification. The
spontaneous currents were inhibited by bicuculline and potentiated by diazepam. It was concluded that the spontaneously opening
channels were constitutively active, nonsynaptic GABAA channels. Such spontaneously opening GABAA channels may provide a tonic inhibitory mechanism in these cells and perhaps in other cells that have GABAA receptors although not having a GABAA synaptic input. They may also be a target for clinically useful drugs such as the benzodiazepines.
Received: 31 August 1999/Revised: 2 November 1999 |
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Keywords: | : Ion channel — Ligand-gated — Patch clamp — Single-channel recording — Anesthetics — Inhibition |
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