Uptake of Gaba and L-Glutamate Into Synaptic Vesicles
Synaptic vesicles are supposed to play a central role in neurotransmission as the transmitter storing and releasing organelles of the nerve terminal. In the central nervous system y-aminobutyric acid (GABA) and L-glutamate are the most important inhibitory and excitatory neurotransmitters, respectively (Krnjevic, 1970). There are, however, no evidence for any enrichment of GABA and L-glutamate in the synaptosomes or the synaptic vesicles compared to other subcellular fractions from brain tissue (De Belleroche and Bradford, 1973; Lahdesmaki et. al., 1977; Wood and Kurylo, 1984). The lack of evidence for an enrichment of GABA and L-glutamate has been attributed to the possible leakage of the amino acids during the isolation procedure. It has been shown that GABA and L-glutamate are taken up into isolated synaptic vesicles by an active transport mechanism (Philippu and Matthaei, 1975; Disbrow et al., 1982; Naito and Ueda, 1983; Fykse and Fonnum, 1988). The vesicular uptake is temperature dependent, and dependent on the presence of ATP and Mg2+ the incubation medium. The vesicular uptake is not dependent on Na+, and it is not inhibited by blockers of the glial and synaptosomal uptake.
KeywordsHistamine Catecholamine Acetylcholine Lamines Colchicine
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