GABA and chloride permeate via the same channels across single plasma membranes microdissected from rabbit Deiters’ vestibular neurones

Abstract

The permeation of labelled gamma-aminobutyric acid (GABA) across single microdissected Deiters' membranes has been studied in a microchamber system. The GABA permeation is via pores which are blocked by 4,4'-diisothiocyanato stilbene-2-2'disulphonic acid (DIDS). As this substance blocks as well chloride permeation across these membranes we tested whether GABA and chloride permeate across the same pores. Membrane pre-treatment with different doses of corticotropin releasing factor (CRF), a membrane permeant cyclic AMP analogue and phalloidin parallelly block the permeation of the two substances. Thus, it is most probable that GABA and chloride pass across the same pores. These pores may be swelling activated ones, opened by the mechanical stress on the membranes in the microchamber system. The passage of GABA across these pores may be of physiological importance in the termination of GABA inhibitory action on the vestibular Deiters' neurones.

Pharmacological Analysis of the Activation and Receptor Properties of the Tonic GABACR Current in Retinal Bipolar Cell Terminals

“…BCTs are surrounded by amacrine cell processes that make the conventional GABAergic synapses that mediate reciprocal and lateral feedback inhibition [53]. Although non-vesicular neurotransmitter release is thought to occur primarily from glial cells, DIDS-sensitive GABA-permeable anion channels have been observed in Deiters neurons in the brainstem [54]. Müller cells, the principle glial cells of the retina, are known to release neuroactive substances such as ATP, with consequent effects on synaptic activity and spiking in ganglion cells [55].…”