Use of 3h-. gamma. -aminobutyric acid for transport studies with isolated nerve-terminals from rat brain
Isolated synaptosomes were used to study the problem of net accumulation of neurotransmitters. The time-course and the kinetics of exogenous and endogenous GABA transport were studied by liquid-scintillation counting and HPLC-amino acid analysis respectively. Different pools of GABA were suggested by a 6-fold difference in tissue-to-medium-ratio of endogenous vs. exogenous GABA. Net accumulation, exchange and net efflux of GABA was found to be a function of the GABA concentration in the incubation medium. The K/sub m/s for net accumulation and for /sup 3/H-GABA accumulation were 2.68 +/- 1.16 and 6.19 +/- 1.26 ..mu..M respectively, whereas the V/sub max/s were 5.9 +/- 4.9 and 134 +/- 13 pmol/mg w.w min respectively. This means that the transport studies which use exogenous substances (e.g. /sup 3/H-GABA) considerably overestimate the transport by overlooking the magnitude of the counter transport. 22 references, 5 figures, 2 tables.
- Research Organization:
- National Defense Research Institute, Umea, Sweden
- OSTI ID:
- 5569558
- Journal Information:
- Life Sci.; (United States), Vol. 37:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMINOBUTYRIC ACID
MEMBRANE TRANSPORT
BIOCHEMICAL REACTION KINETICS
BIOELECTRICITY
BRAIN
LIQUID COLUMN CHROMATOGRAPHY
NERVE CELLS
RATS
SCINTILLATION COUNTING
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMINO ACIDS
ANIMAL CELLS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
CARBOXYLIC ACIDS
CENTRAL NERVOUS SYSTEM
CHROMATOGRAPHY
COUNTING TECHNIQUES
DRUGS
ELECTRICITY
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
NERVOUS SYSTEM
NEUROREGULATORS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
REACTION KINETICS
RODENTS
SEPARATION PROCESSES
SOMATIC CELLS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques