Astrocytes exhibit three transmembrane Ca 2+ influx pathways: voltage-gated Ca 2+ channels (VGCCs), the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) class of glutamate receptors, and Na + /Ca 2+ exchangers. Each of these pathways is thought to be capable of mediating a significant increase in Ca 2+ concentration ((Ca 2+ ) i ); however, the relative importance of each and their interdependence in the regulation astrocyte (Ca 2+ ) i is not known. We demonstrate here that 100 μM AMPA in the presence of 100 μM cyclothiazide (CTZ) causes an increase in (Ca 2+ ) i in cultured cerebral astrocytes that requires transmembrane Ca 2+ influx. This increase of (Ca 2+ ) i is blocked by 100 μM benzamil or 0.5 μM U-73122, which inhibit reverse-mode operation of the Na + /Ca 2+ exchanger by independent mechanisms. This response does not require Ca 2+ influx through VGCCs, nor does it depend upon a significant Ca 2+ influx through AMPA receptors (AMPARs). Additionally, AMPA in the presence of CTZ causes a depletion of thapsigargin-sensitive intracellular Ca 2+ stores, although depletion of these Ca 2+ stores does not decrease the peak (Ca 2+ ) i response to AMPA. We propose that activation of AMPARs in astrocytes can cause (Ca 2+ ) i to increase through the reverse mode operation of the Na + /Ca 2+ exchanger with an associated release of Ca 2+ from intracellular stores. This proposed mechanism requires neither Ca 2+ -permeant AMPARs nor the activation of VGCCs to be effective.
Brain Research – Elsevier
Published: Dec 22, 2000
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera