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Spontaneous and action potential-evoked Ca2+ release from endoplasmic reticulum in neocortical synaptic boutons

Spontaneous and action potential-evoked Ca2+ release from endoplasmic reticulum in neocortical synaptic boutons

Authors :
Christian Stricker
Van Tran
Source :
Cell Calcium. 97:102433
Publication Year :
2021
Publisher :
Elsevier BV, 2021.

Abstract

Although the endoplasmic reticulum (ER) is present throughout axons, and IP3 and ryanodine receptors are widely expressed in nerve terminals, whether Ca2+ release from presynaptic stores contributes to action potential (AP)-evoked Ca2+ transients remains controversial. We investigated the release of Ca2+ from ER stores in boutons en passant of neocortical layer 5 pyramidal neurons. A hallmark of these stores is that they spontaneously release Ca2+ at a low frequency. Using a high-affinity Ca2+ indicator, we documented and characterised such spontaneous Ca2+ transients (sCaTs), which occurred at a rate of ~0.2 per min and raised the intracellular Ca2+ concentration ([Ca2+]i) by ~2 µM in the absence of exogenous buffers. Caffeine increased the average frequency of sCaTs by 90%, without affecting their amplitude and decay kinetics. Therefore, presynaptic ryanodine receptors were likely involved. To determine if presynaptic ER stores contribute to intracellular Ca2+ accumulation during repetitive stimulation, we measured [Ca2+]i during 2 s long trains of APs evoked at 10-50 Hz. We found that for frequencies

Details

ISSN :
01434160
Volume :
97
Database :
OpenAIRE
Journal :
Cell Calcium
Accession number :
edsair.doi...........5da61e93bd24e69837e752e0b05a16b8
Full Text :
https://doi.org/10.1016/j.ceca.2021.102433