Chloride permeation across the Deiters' neuron plasma membrane: activation by GABA on the membrane cytoplasmic side

• Published in: Neuroscience Vol. 89; no. 4; pp. 1391 - 1400
• Main Authors: Hydén, H, Cupello, A, Rapallino, M.V
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1999; Elsevier
• Subjects: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid - pharmacology; Animals; Bicuculline - pharmacology; Biological and medical sciences; Biological Transport - drug effects; Cell Membrane - drug effects; Cell Membrane - physiology; Central nervous system; Chlorides - metabolism; Cl − extrusion; Deiters' neuron; Electrophysiology; Fundamental and applied biological sciences. Psychology; GABA A receptors; GABA-A Receptor Antagonists; gamma-Aminobutyric Acid - pharmacology; In Vitro Techniques; intracellular GABA; Iodides - pharmacology; Kinetics; Male; Models, Neurological; Neurons - drug effects; Neurons - physiology; Rabbits; Receptors, GABA-A - physiology; single membranes; Vertebrates: nervous system and sense organs; Vestibular Nucleus, Lateral - physiology; Zinc - pharmacology; Cl − extrusion; ClC- n, chloride channel- n; intracellular GABA; Deiters' neuron; GABA A receptors; PB, (±)-pentobarbitone; HEPES, N-2-hydroxyethylpiperazine- N′-2-ethanesulphonic acid; single membranes; BMI, (−)-bicuculline methiodide; DIDS, 4,4′-diisothiocyanatostilbene-2,2′-disulphonic acid; Central nervous system; Permeation; Rabbit; Ionic current; Lagomorpha; Vertebrata; Mammalia; Chlorides; Vestibular nucleus; Vestibular pathway; Plasma membrane; Neurotransmitter; GABA; Deiters nucleus; Gabaergic receptor A; Brain (vertebrata)
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(98)00357-1

Single plasma membranes were microdissected from Deiters' neurons freshly obtained from the lateral vestibular nucleus of the rabbit and their chloride permeability was studied in a microchamber system. The basal in→out
36Cl
− permeation initially found was brought to zero by Zn
2+, 4,4′-diisothiocyanatostilbene-2,2′-disulphonic acid and iodide. GABA on the membrane cytoplasmic side resulted in a measurable in→out
36Cl
− passage, which was blocked by the GABA
A antagonists bicuculline and picrotoxin. This effect peaked at 1
μM GABA on the inner side of the membrane. At higher GABA concentrations, a strong desensitization of the effect was found. Stimulation of Cl
− permeability by GABA on the extracellular side of the membrane peaked at much higher GABA concentrations, 10–100
μM. This excludes an effect due to passage of the neurotransmitter from the inner to the outer compartment in our microchamber device. Moreover, this possibility is also dismissed by the fact that 1
μM GABA on the membrane outside did not evoke any
36Cl
− in→out permeation. In addition, pentobarbitone by itself could also stimulate
36Cl
− in→out permeation when added on the cytoplasmic side of Deiters' membrane.
On these bases and in agreement with our previous reports, we propose that structures behaving pharmacologically as GABA
A receptors respond to low levels of GABA on the cytoplasmic side of these neurons' membranes. We suggest that these structures are devices that, at the expense of ATP consumed in their phosphorylation, extrude Cl
− after postsynaptic GABA uptake into the Deiters' neuron.