Subsecond kinetics of synaptosomal sup 3 H-. gamma. -aminobutyric acid release, and the relationship to presynaptic Ca sup +2 channels

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6948521

Turner, T J

A subcellular preparation of rat brain enriched in nerve terminals was used to study the biochemistry and pharmacology of Ca{sup +2} entry and presynaptic neurotransmitter release. Synaptosomes maintained a membrane potential and supported a biphasic depolarization-stimulated {sup 45}Ca{sup +2} uptake. Replacing external Na{sup +} with the impermeant cation choline eliminated the slower of the two phases, leaving an uptake process that terminated within one second. A portion of the remaining rapid phase of {sup 45}Ca{sup +2} uptake is dihydropyridine-sensitive. Because synaptosomal Ca{sup +2} uptake is mediated by multiple pathways, the release of neurotransmitter was studied as a means to focus on Ca{sup +2} entry at nerve terminals important to excitation-secretion coupling. A superfusion method was developed to measure synaptosomal neurotransmitter release on a time scale approaching the real time course of synaptic events. Synaptosomes prelabeled with {sup 3}H-{gamma}-aminobutyric acid ({sup 3}H-GABA) were retained on glass fiber filters in a superfusion chamber accessed by three solenoid-driven values. The minimal dead volume of the chamber and the relatively high solution flow rate affords time resolution for release of at least 60 msec. This time resolution was necessary to observe three distinct components of GABA release.

• Research Organization: Harvard Univ., Boston, MA (USA)
• OSTI ID: 6948521
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
AMINO ACIDS
AMINOBUTYRIC ACID
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMISTRY
BIOELECTRICITY
BIOLOGICAL PATHWAYS
BODY
BRAIN
CALCIUM 45
CALCIUM COMPOUNDS
CALCIUM ISOTOPES
CARBOXYLIC ACIDS
CENTRAL NERVOUS SYSTEM
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRICITY
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANE TRANSPORT
NERVES
NERVOUS SYSTEM
NEUROREGULATORS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
RADIOISOTOPES
RATS
RODENTS
SECRETION
TRACER TECHNIQUES
VERTEBRATES