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THE EFFECT OF ELECTRICAL STIMULATION AND HIGH POTASSIUM CONCENTRATIONS ON THE EFFLUX OF [ 3 H] γ‐AMINOBUTYRIC ACID FROM BRAIN SLICES
Author(s) -
Srinivasan Vasanta,
Neal M. J.,
Mitchell J. F.
Publication year - 1969
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.1471-4159.1969.tb05971.x
Subject(s) - aminooxyacetic acid , efflux , stimulation , potassium , chemistry , aminobutyric acid , glutamate receptor , gamma aminobutyric acid , inhibitory postsynaptic potential , medicine , biochemistry , endocrinology , biophysics , biology , receptor , organic chemistry , enzyme
Abstract— Brain slices were incubated with [ 3 H]GABA in a medium containing aminooxyacetic acid to prevent metabolism of [ 3 H]GABA by GABA‐glutamate transaminase. The slices, which rapidly accumulated radioactivity, were then continuously perfused and the efflux of [ 3 H]GABA from the tissue was measured. The spontaneous efflux of [ 3 H]GABA consisted of an initial rapid phase followed by a much slower release of [ 3 [H]GABA. After 40 min perfusion 90 per cent of the radioactivity remained in the tissue. The slices were depolarized by electrical stimulation or by perfusion with a medium containing a high potassium concentration (40 mM). These procedures caused a striking increase in the efflux of [ 3 H]GABA. The increased efflux produced by potassium, but not that produced by electrical stimulation, was dependent on calcium ions in the medium. The effect of electrical stimulation on [ 3 H]GABA release was considerably reduced by a raised concentration (10 mM) of magnesium in the medium. High potassium concentrations and electrical stimulation did not cause an increase in the efflux of [ 14 C]urea, L‐[ 3 H]leucine or [ 14 C]α‐amino‐isobutyric acid from brain slices. These results are consistent with the suggestion that GABA may be an inhibitory transmitter in the cerebral cortex.