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THE UPTAKE OF [ 3 H]GABA BY SLICES OF RAT CEREBRAL CORTEX
Author(s) -
Iversen L. L.,
Neal M. J.
Publication year - 1968
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.1471-4159.1968.tb06831.x
Subject(s) - ouabain , cerebral cortex , chemistry , glycine , dinitrophenol , inhibitory postsynaptic potential , incubation , gamma aminobutyric acid , alanine , cortex (anatomy) , glutamic acid , sodium , amino acid , biophysics , biochemistry , biology , endocrinology , receptor , neuroscience , organic chemistry
—A rapid accumulation of [ 3 H]GABA occurs in slices of rat cerebral cortex incubated at 25° or 37° in a medium containing [ 3 H]GABA. Tissue medium ratios of almost 100:1 are attained after a 60 min incubation at 25°. At the same temperature no labelled metabolites of GABA were found in the tissue or the medium. The process responsible for [ 3 H]GABA uptake has many of the properties of an active transport mechanism: it is temperature sensitive, requires the presence of sodium ions in the external medium, is inhibited by dinitrophenol and ouabain, and shows saturation kinetics. The estimated K m value for GABA is 2·2 × 10 −5 m , and V max is 0·115 μmoles/min/g cortex. There is only negligible efflux of the accumulated [ 3 H]GABA when cortical slices are exposed to a GABA‐free medium. [ 3 H]GABA uptake was not affected by the presence of large molar excesses of glycine, l ‐glutamic acid, l ‐aspartic acid, or β‐aminobutyrate, but was inhibited in the presence of l ‐alanine, l ‐histidine, β‐hydroxy‐GABA and β‐guanidinopropionate. It is suggested that the GABA uptake system may represent a possible mechanism for the inactivation of GABA or some related substance at inhibitory synapses in the cortex.