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Journal article
Barium Evokes Glutamate Release from Rat Brain Synaptosomes by Membrane Depolarization: Involvement of K+, Na+, and Ca2+ Channels
Journal of neurochemistry, v 61(4), pp 1220-1230
Oct 1993
PMID: 7690845
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
: During K+ ‐induced depolarization of isolated rat brain nerve terminals (synaptosomes), 1 mM Ba2+ could substitute for 1 mM Ca2+ in evoking the release of endogenous glutamate. In addition, Ba2+ was found to evoke glutamate release in the absence of K+‐induced depolarization. Ba2+ (1–10 mM) depolarized synaptosomes, as measured by voltage‐sensitive dye fluorescence and [3H]‐tetraphenylphosphonium cation distribution. Ba2+ partially inhibited the increase in synaptosomal K+ efflux produced by depolarization, as reflected by the redistribution of radiolabeled 86Rb+. The release evoked by Ba2+ was inhibited by tetrodotoxin (TTX). Using the divalent cation indicator fura‐2, cytosolic [Ca2+] increased during stimulation by approximately 200 nM, but cytosolic [Ba2+] increased by more than 1 μM. Taken together, our results indicate that Ba2+ initially depolarizes synaptosomes most likely by blocking a K+ channel, which then activates TTX‐sensitive Na+ channels, causing further depolarization, and finally enters synaptosomes through voltage‐sensitive Ca2+channels to evoke neurotransmitter release directly. Though Ba2+‐evoked glutamate release was comparable in level to that obtained with K+‐induced depolarization in the presence of Ca2+, the apparent intrasynaptosomal level of Ba2+ required for a given amount of glutamate release was found to be several‐fold higher than that required of Ca2+.
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Details
- Title
- Barium Evokes Glutamate Release from Rat Brain Synaptosomes by Membrane Depolarization: Involvement of K+, Na+, and Ca2+ Channels
- Creators
- Talvinder S. Sihra - Woman's Medical College of PennsylvaniaDaniele Piomelli - Woman's Medical College of PennsylvaniaRobert A. Nichols - Woman's Medical College of Pennsylvania
- Publication Details
- Journal of neurochemistry, v 61(4), pp 1220-1230
- Publisher
- Blackwell Publishing Ltd
- Number of pages
- 11
- Resource Type
- Journal article
- Language
- English
- Web of Science ID
- WOS:A1993LY32500003
- Scopus ID
- 2-s2.0-0027524824
- Other Identifier
- 991019350583004721
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InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Web of Science research areas
- Biochemistry & Molecular Biology
- Neurosciences