"Intracellular" GABA affects the equilibrium distribution of Cl- across the plasma membrane of a GABA acceptive neuron.
The permeability of Cl- ions through single microdissected plasma membrane from Deiters' neurons was studied by a microtechnique. In particular, the time course of the passage of 36Cl- ions from a microchamber, M1, to another one, M2, across the membrane was followed. This study was performed with or without gamma-amino-butyric acid (GABA) in the two microchambers. The results suggest that in basal conditions the high intracellular concentration normally present in these neurons, 3.3 mM (1), causes a higher permeability of Cl- in the direction inside----outside in the respect of the plasma membrane. "Extracellular" GABA, 0.1 mM, is able to abolish this imbalance in Cl- permeability in the two opposite directions. This event appears to be the basis for GABA induced hyperpolarization of these neurons.
Hydén
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Institute of Neurobiology, University of Göteborg, Sweden.
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Palm
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D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D002712:Chlorides / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D010852:Picrotoxin / Q000494:pharmacology; D013997:Time Factors; D003689:Vestibular Nucleus, Lateral / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D001640:Bicuculline; D002712:Chlorides; D010852:Picrotoxin; D005680:gamma-Aminobutyric Acid