Abstract
1. Studies about the permeation of labelled chloride and GABA across single plasma membranes microdissected from vestibular Deiters' neurons have yielded two unexpected results: (a) intracellular GABA stimulates chloride permeation in an asymmetric fashion (efflux being favoured); (b) under certain conditions GABA permeates by a diffusion mechanism in the out-->in direction across these plasma membranes. 2. These two main results have been obtained over many years together with a host of other indications about the fine mechanism of these events. Thus, a picture has emerged of their physiological meaning within the context of the functioning of the GABAA synapses between the Purkinje cells and the Deiters' neurons. 3. In short, it is proposed that at these synapses GABA accumulates into the postsynaptic neuron after its release and activation of the postsynaptic receptors. GABA accumulated in the Deiters' neurons is involved in the process of chloride extrusion to build an inward directed electrochemical gradient for chloride.