Abstract |
Injections of inositol trisphosphate (IP3) or nicotinamide adenine dinucleotide phosphate ( NAADP) into the presynaptic neurone of an identified cholinergic synapse in the buccal ganglion of Aplysia californica increased the amplitude of the inhibitory postsynaptic current evoked by a presynaptic action potential. This suggests that Ca2+ release from various Ca2+ stores can modulate acetylcholine (ACh) release. Specific blockade of the calcium-induced calcium release (CICR) mechanism with ryanodine, or of IP3-induced calcium release with heparin, abolished the effects of IP3, but not the effects of NAADP, suggesting the presence of an intracellular Ca2+ pool independent of those containing ryanodine receptors (RyR) or IP3 receptors. To reinforce electrophysiological observations, intracellular [Ca2+]i changes were measured using the fluorescent dye rhod-2. Injections of cyclic ADP-ribose (an activator of RyR), IP3 or NAADP into the presynaptic neurone induced transient increases in the free intracellular Ca2+ concentration. RyR- and IP3-induced increases were prevented by application of respective selective antagonists but not NAADP-induced increases. Our results show that RyR-dependent, IP3-dependent, and NAADP-dependent Ca2+ stores are present in the same presynaptic terminal but are differently involved in the regulation of the presynaptic Ca2+ concentration that triggers transmitter release.
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Authors | P Chameau, Y Van de Vrede, P Fossier, G Baux |
Journal | Pflugers Archiv : European journal of physiology
(Pflugers Arch)
Vol. 443
Issue 2
Pg. 289-96
(Nov 2001)
ISSN: 0031-6768 [Print] Germany |
PMID | 11713656
(Publication Type: Journal Article)
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Chemical References |
- Ryanodine Receptor Calcium Release Channel
- Ryanodine
- NADP
- NAADP
- Inositol 1,4,5-Trisphosphate
- Acetylcholine
- Calcium
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Topics |
- Acetylcholine
(metabolism)
- Animals
- Aplysia
- Biological Transport
- Calcium
(physiology)
- Cheek
(innervation)
- Ganglia
(drug effects, metabolism)
- In Vitro Techniques
- Inositol 1,4,5-Trisphosphate
(pharmacology)
- Intracellular Membranes
(metabolism)
- NADP
(analogs & derivatives, pharmacology)
- Ryanodine
(pharmacology)
- Ryanodine Receptor Calcium Release Channel
(physiology)
- Synaptic Transmission
(physiology)
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