| Autor: |
Wei Xiong, Tao Liu, Yeshi Wang, Xiaowei Chen, Lei Sun, Ning Guo, Hui Zheng, Lianghong Zheng, Martial Ruat, Weiping Han, Claire Xi Zhang, Zhuan Zhou |
| Jazyk: |
angličtina |
| Rok vydání: |
2011 |
| Předmět: |
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| Zdroj: |
PLoS ONE, Vol 6, Iss 10, p e24573 (2011) |
| Druh dokumentu: |
article |
| ISSN: |
1932-6203 |
| DOI: |
10.1371/journal.pone.0024573 |
| Popis: |
AIM: Neurotransmitter release is elicited by an elevation of intracellular Ca(2+) concentration ([Ca(2+)](i)). The action potential triggers Ca(2+) influx through Ca(2+) channels which causes local changes of [Ca(2+)](i) for vesicle release. However, any direct role of extracellular Ca(2+) (besides Ca(2+) influx) on Ca(2+)-dependent exocytosis remains elusive. Here we set out to investigate this possibility on rat dorsal root ganglion (DRG) neurons and chromaffin cells, widely used models for studying vesicle exocytosis. RESULTS: Using photolysis of caged Ca(2+) and caffeine-induced release of stored Ca(2+), we found that extracellular Ca(2+) inhibited exocytosis following moderate [Ca(2+)](i) rises (2-3 µM). The IC(50) for extracellular Ca(2+) inhibition of exocytosis (ECIE) was 1.38 mM and a physiological reduction (∼30%) of extracellular Ca(2+) concentration ([Ca(2+)](o)) significantly increased the evoked exocytosis. At the single vesicle level, quantal size and release frequency were also altered by physiological [Ca(2+)](o). The calcimimetics Mg(2+), Cd(2+), G418, and neomycin all inhibited exocytosis. The extracellular Ca(2+)-sensing receptor (CaSR) was not involved because specific drugs and knockdown of CaSR in DRG neurons did not affect ECIE. CONCLUSION/SIGNIFICANCE: As an extension of the classic Ca(2+) hypothesis of synaptic release, physiological levels of extracellular Ca(2+) play dual roles in evoked exocytosis by providing a source of Ca(2+) influx, and by directly regulating quantal size and release probability in neuronal cells. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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