title: Modulation by calcium of Deiters' neuron GABAA receptors in the rabbit.
abstract: The function of classical GABAA receptors of the rabbit Deiters' neurons has been studied at the single membrane level by a biochemical micromethod involving the study of labelled chloride permeation. In particular, labelled chloride permeation across microdissected fresh single membranes was studied in a microchamber system. The stimulation of 36Cl- out-->in permeation by "extracellular" GABA was determined under different conditions in the respect of Ca++. When the conditions were such that "intracellular" Ca++ was 0.02 microM there appeared to be an optimal effect by GABA on chloride passage. Conditions presumably resulting in an increase of [Ca++]i beyond the level reported above led to a decreased GABA effect, especially at the highest GABA concentrations used (> or = 10(-4)M). However, complete removal of Ca++ by a high (12 mM) intracellular EGTA concentration erased completely the GABA effect. These results indicate that in these neurons an optimal GABAA receptor function requires [Ca++]i levels well below micromolar. The high [EGTA]i effect seems to imply that too low a [Ca++]i is also harmful to the proper function of these GABAA receptors. However, an alternative explanation is possible.
authors.affiliation: Institute of Neurobiology, University of Goteborg, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Hydén
authors.forename: A
authors.initials: A
authors.lastname: Cupello
authors.forename: M V
authors.initials: MV
authors.lastname: Rapallino
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002463:Cell Membrane Permeability / Q000187:drug effects; D004533:Egtazic Acid / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D008297:Male; D011817:Rabbits; D018079:Receptors, GABA / Q000187:drug effects*; D003689:Vestibular Nucleus, Lateral / Q000187:drug effects*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D018079:Receptors, GABA; D004533:Egtazic Acid; D005680:gamma-Aminobutyric Acid; D002118:Calcium