Logo image
Back
Barium Evokes Glutamate Release from Rat Brain Synaptosomes by Membrane Depolarization: Involvement of K+, Na+, and Ca2+ Channels
Journal article   Open access   Peer reviewed

Barium Evokes Glutamate Release from Rat Brain Synaptosomes by Membrane Depolarization: Involvement of K+, Na+, and Ca2+ Channels

Talvinder S. Sihra, Daniele Piomelli and Robert A. Nichols
Journal of neurochemistry, v 61(4), pp 1220-1230
Oct 1993
DOI: https://doi.org/10.1111/j.1471-4159.1993.tb13612.x
PMID: 7690845
Featured in Collection :   UN Sustainable Development Goals @ Drexel
url
https://escholarship.org/uc/item/4428v136View
SubmittedCC BY V4.0,  Open

Abstract

Barium Calcium Glutamate Ion channels Neurotransmitter release Synaptosomes
: 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+.

Metrics

7 Record Views
38 citations in Web of Science
37 citations in Scopus

Details

UN Sustainable Development Goals (SDGs)

This publication has contributed to the advancement of the following goals:

#3 Good Health and Well-Being

InCites Highlights

Data related to this publication, from InCites Benchmarking & Analytics tool:

Web of Science research areas
Biochemistry & Molecular Biology
Neurosciences
Logo image