The contribution of intracellular calcium stores to mEPSCs recorded in layer II neurones of rat barrel cortex

Loading slices of rat barrel cortex with 50 μ m BAPTA-AM while recording from pyramidal cells in layer II induces a marked reduction in both the frequency and amplitudes of mEPSCs. These changes are due to a presynaptic action. Blocking the refilling of Ca 2+ stores with 20 μ m cyclopiazonic acid...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:The Journal of physiology 2002-12, Vol.545 (2), p.521-535
Hauptverfasser: Simkus, Christopher R. L., Stricker, Christian
Format: Artikel
Sprache:eng
Schlagworte:
Online-Zugang:Volltext
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:Loading slices of rat barrel cortex with 50 μ m BAPTA-AM while recording from pyramidal cells in layer II induces a marked reduction in both the frequency and amplitudes of mEPSCs. These changes are due to a presynaptic action. Blocking the refilling of Ca 2+ stores with 20 μ m cyclopiazonic acid (CPA), a SERCA pump inhibitor, in conjunction with neuronal depolarisation to activate Ca 2+ stores, results in a similar reduction of mEPSCs to that observed with BAPTA-AM, indicating that the source for intracellular Ca 2+ is the endoplasmic reticulum. Block or activation of ryanodine receptors by 20 μ m ryanodine or 10 m m caffeine, respectively, shows that a significant proportion of mEPSCs are caused by Ca 2+ release from ryanodine stores. Blocking IP 3 receptors with 14 μ m 2-aminoethoxydiphenylborane (2APB) also reduces the frequency and amplitude of mEPSCs, indicating the involvement of IP 3 stores in the generation of mEPSCs. Activation of group I metabotropic receptors with 20 μ m ( RS) -3,5-dihydroxyphenylglycine (DHPG) results in a significant increase in the frequency of mEPSCs, further supporting the role of IP 3 receptors and indicating a role of group I metabotropic receptors in causing transmitter release. Statistical evidence is presented for Ca 2+ -induced Ca 2+ release (CICR) from ryanodine stores after the spontaneous opening of IP 3 stores.
ISSN:0022-3751
1469-7793
DOI:10.1113/jphysiol.2002.022103