English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The present experiments investigated the effect of some of the toxic components present in the venom of the spider Phoneutria nigriventer on the release of neurotransmitter. The toxic fraction, Phoneutria nigriventer toxin-3 (PhTx3), abolished Ca2+-dependent glutamate release, but did not alter Ca2+-independent secretion of glutamate when rat brain cortical synaptosomes were depolarized with 33 mM KCl. This effect was most likely due to interference with the entry of calcium through voltage-gated calcium channels, because PhTx3 reduced by 50% the increase in intrasynaptosomal free calcium induced by membrane depolarization, and did not affect the release of glutamate evoked by a calcium ionophore (ionomycin). A polypeptide (Tx3-3) present in the PhTx3 fraction reproduced the effects of the PhTx3 fraction on transmitter release and intrasynaptosomal free calcium in the low nanomolar range. We compared the alterations produced by the Tx3-3 with the actions of toxins known to block calcium channels coupled to exocytosis: the results indicated that the Tx3-3 inhibition of glutamate release and intrasynaptosomal calcium resemble that observed with omega-conotoxin MVIIC. We suggest that the Tx3-3 is a calcium-channel antagonist that blocked glutamate exocytosis.

biochemical journal

A novel tool for the investigation of glutamate release from rat cerebrocortical synaptosomes: the toxin Tx3-3 from the venom of the spider <i>Phoneutria nigriventer</i>

A novel tool for the investigation of glutamate release from rat cerebrocortical synaptosomes: the toxin Tx3-3 from the venom of the spider Phoneutria nigriventer