Abstract
Activation of NMDA receptors produces large increases in cytosolic Ca 2+ that are taken up into mitochondria. We used recombinant aequorin targeted to mitochondria to report changes in matrix Ca2+ in rat hippocampal neurons in culture. Upon binding Ca2+, aequorin emits a photon in a one-shot reaction that consumes the indicator. Here we show that stimulation with NMDA produced a mitochondrial Ca2+ response that rapidly inactivated. However, following a 30-min recovery period the response was restored, suggesting the presence of a pool of indicator that was not exposed to high Ca2+ during the initial stimulus. We speculate that aequorin distant from the Ca2+ source was protected from microdomains of high Ca2+ near the plasmalemma and that this aequorin moved, either by movement of individual mitochondria or via the mitochondrial tubular network, to replenish consumed indicator during the recovery time. A large Ca2+ increase in a subset of mitochondria could produce local changes in energy metabolism, regional Ca2+ buffering, and foci that initiate neurotoxic processes.
Original language | English (US) |
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Pages (from-to) | 124-132 |
Number of pages | 9 |
Journal | Brain Research |
Volume | 993 |
Issue number | 1-2 |
DOIs | |
State | Published - Dec 12 2003 |
Bibliographical note
Funding Information:This work was supported by grants from the National Institute on Drug Abuse (DA7304, DA11806) and the National Science Foundation (IBN0110409).
Keywords
- Aequorin
- Ca microdomains
- Excitotoxicity
- Mitochondria
- NMDA
- [Ca]