SUBCELLULAR DISTRIBUTION OF ENDOGENOUS AND [3H] γ-AMINOBUTYRIC ACID IN RAT CEREBRAL CORTEX |
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Authors: | M J Neal L L Iversen |
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Institution: | Department of Pharmacology, University of Cambridge, Cambridge, England |
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Abstract: | Abstract— Slices of rat cerebral cortex were labelled by incubation with 3H]γ-aminobutyric acid (GABA) and homogenized in isotonic sucrose. The subcellular distributions of endogenous GAB A, 3H]GABA and glutamate decarboxylase (GAD) were studied by density gradient centrifugation. The subcellular distributions of the labelled and endogenous amino acid were remarkably similar, indicating that 3H]GABA is taken up into the endogenous GABA pool. About 40 per cent of both endogenous and 3H]GABA were recovered in particles which were tentatively identified as synaptosomes from their equilibrium density and sensitivity to osmotic shock. In slices labelled with 3H]GABA and 14C]α-aminoisobutyric (AIB) acid, significantly more 3H]GABA was recovered in paniculate fractions than 14C]AIB. About 80 per cent of the enzyme GAD was also recovered in the same particle fractions which contained 3H]GABA and endogenous GABA. Evidence is presented which suggests that a loss of particle-bound GABA occurs during subcellular fractionation procedures. |
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