Published 1989 | Version v1
Miscellaneous

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

Description

A subcellular preparation of rat brain enriched in nerve terminals was used to study the biochemistry and pharmacology of Ca+2 entry and presynaptic neurotransmitter release. Synaptosomes maintained a membrane potential and supported a biphasic depolarization-stimulated 45Ca+2 uptake. Replacing external Na+ 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 45Ca+2 uptake is dihydropyridine-sensitive. Because synaptosomal Ca+2 uptake is mediated by multiple pathways, the release of neurotransmitter was studied as a means to focus on Ca+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 3H-γ-aminobutyric acid (3H-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

Availability note (English)

University Microfilms, PO Box 1764, Ann Arbor, MI 48106, Order No.89-14,704.

Additional details

Publishing Information

Publisher
Harvard Univ.
Imprint Place
Cambridge, MA (USA)
Imprint Pagination
227 p.