GABA(A) receptor activation triggers a Cl- conductance increase and a K+ channel blockade in cerebellar granule cells (Journal article)

Labrakakis, C./ Muller, T./ Schmidt, K./ Kettenmann, H.


GABA(A) receptor activation in cerebellar granule cells induced a complex physiological response, namely the activation of a Cl- conductance in concert with a blockade of the resting K+ outward conductance (by 71% as compared to controls). Both responses were mediated by the activation of GABA(A) receptors, since they were both mimicked by the GABA(A) receptor agonist muscimol and antagonized by picrotoxin and bicuculline. A substantial decrease of the mean open time of single, outwardly rectifying K+ channels was triggered by GABA as revealed from cell-attached recordings; this finding implies that an intracellular pathway links GABA(A) receptors and K+ channels. Furthermore, this action of GABA is mediated through the cytoplasm, as experiments with the cell-attached patch-clamp technique show. GABA induced a prominent membrane depolarization ranging from 10 to 25 mV as revealed by current-clamp recordings of gramicidin (or nystatin) permeabilized patches, thus selecting conditions not to perturb the physiological Cl- gradient across the cell. Our findings imply that the GABA-activated Cl- current depolarized the membrane as described for immature neurons. The blockade of the resting K+ channel conductance acts in concert and both mechanisms lead to this substantial depolarizing event.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών
Keywords: Animals,Barium/pharmacology,Bicuculline/*pharmacology,Cells, Cultured,Cerebellum/cytology/drug effects/*physiology,Chloride Channels/*physiology,Chlorides/*metabolism,Membrane Potentials/drug effects,Mice,Mice, Inbred Strains,Muscimol/*pharmac
URI: http://olympias.lib.uoi.gr/jspui/handle/123456789/7481
ISSN: 0306-4522
Link: http://www.ncbi.nlm.nih.gov/pubmed/9178874
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