COMPONENTS OF TAURINE EFFLUX IN RAT-BRAIN SYNAPTOSOMES

The efflux of [35S]taurine from isolated rat brain synaptosomes was studied in a superfusion system. The spontaneous efflux of taurine was slow and could be described as comprising two first-order rate components, of which the slower (t 1 2 = 77.0 min) represents release from intrasynaptosomal spaces. Only a high taurine concentration (10 mmol/1) in the medium enhanced the efflux of intrasynaptosomal taurine, which indicates a rather stable intrasynaptosomal taurine compartment. Depolarizing concentrations of potassium ions stimulated taurine efflux and also induced the appearance of a new 'intermediate' efflux component. This component was absent when calcium ions were omitted from the medium. It is therefore suggested that the component may originate from the emptying of synaptic vesicles. © 1979.