ACCELERATED EFFLUX OF [¹⁴C] AND [³H] AMINO ACIDS FROM SUPERFUSED SLICES OF RAT BRAIN

Abstract— The rate of spontaneous efflux of several isotopically‐labelled amino acids was measured in superfused slices of rat brain. The group specificity of amino acid efflux was studied by examining the pattern of accelerated efflux in the presence of extracellular unlabeled amino acid. The mediated efflux of γ‐aminobutyric acid and l‐glutamic acid was highly specific. Less specificity was found for amino acids in the small neutral, large neutral and basic groups. The efflux of γ‐aminobutyric acid and l‐glutamic acid was accelerated by structurally similar amino acids which are known to depress or excite motor neurons. This finding raises the possibility that the physiological effects of non‐specific amino acids during local iontophoresis may be secondary to an accelerated release of more specific transmitter amino acids from neighbouring cells.