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UPTAKE, RELEASE AND HOMO‐ AND HETERO‐EXCHANGE DIFFUSIONS OF INHIBITORY AMINO ACIDS IN GUINEA‐PIG CEREBELLAR SLICES
Author(s) -
Okamoto Koichi,
Namima Misako
Publication year - 1978
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1978.tb06564.x
Subject(s) - taurine , glycine , alanine , amino acid , chemistry , cerebellum , inhibitory postsynaptic potential , biochemistry , glycine receptor , neurotransmitter , biophysics , biology , endocrinology , receptor
— GABA, taurine and β‐alanine are taken up by guinea‐pig cerebellar slices by both the high‐and low‐affinity uptake processes, whereas glycine is taken up only by the low‐affinity process. A considerable amount of labelled GABA loaded in the slice is released by unlabelled external GABA and a minute amount is released by external β‐alanine, glycine and taurine. External glycine and β‐alanine releases labelled glycine loaded in the slice. Labelled taurine loaded is effectively released by external taurine and β‐alanine, while labelled β‐alanine loaded is released only by external β‐alanine. It is suggested that hetero‐exchanges which are one‐directional in some cases also take place between the amino acids in addition to homo‐exchanges. Therefore, high‐affinity uptake processes observed with GABA and taurine could be the result of the homo‐exchange diffusions, while that of β‐alanine could be due to either the homo‐exchange or the hetero‐exchange diffusions or both. K + ′‐evoked releases of GABA and to a lesser extent, taurine are partially dependent upon the presence of Ca + in the superfusion media, whereas that of glycine and probably that of β‐alanine, are not, K + ‐evoked releases of labelled GABA and taurine are larger when loaded by their high‐affinity uptake systems than by their low‐affinity uptake processes. The reverse is the case with labelled glycine and β‐alanine. These results do not rule out the possibility that taurine might act as a neurotransmitter in the cerebellum.