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. 1988 Dec;85(23):9336–9340. doi: 10.1073/pnas.85.23.9336

Patch-clamp study of gamma-aminobutyric acid receptor Cl- channels in cultured astrocytes.

J Bormann 1, H Kettenmann 1
PMCID: PMC282734  PMID: 2461568

Abstract

The membrane channels operated by gamma-aminobutyric acid (GABA) were studied in cultured astrocytes from rat cerebral hemispheres by using patch-clamp techniques. The channel properties appeared to be very similar, in many respects, to those present in neuronal cell membranes. The Cl- -selective channels were activated after the sequential binding of two GABA molecules to the receptor, as deduced from the slope of the dose-response curve. Single-channel currents displayed multiple conductance states of 12 pS, 21 pS, 29 pS, and 43 pS, with the main-state conductance being 29 pS. The gating properties could be described by a sequential reaction scheme for agonist-activated channels. GABA-induced whole-cell currents were potentiated by the benzodiazepine receptor agonist diazepam and also, to a lesser extent, by methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate an inverse agonist. In neurons and chromaffin cells, methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate reduces the sensitivity of the GABA receptor, indicating that neuronal and glial GABA/benzodiazepine receptor--Cl- channel complexes are different. Glial GABA receptor channels could be of functional importance in buffering extracellular Cl- in the cleft of the GABAergic synapse.

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Selected References

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