Ca2+ cooperativity in neurosecretion measured using photolabile Ca2+ chelators - PubMed (original) (raw)

Ca2+ cooperativity in neurosecretion measured using photolabile Ca2+ chelators

L Landò et al. J Neurophysiol. 1994 Aug.

Abstract

1. The photolabile Ca2+ chelator DM-nitrophen was injected into crayfish motor neuron terminals and photolyzed with light flashes of different intensity to determine the cooperativity of Ca2+ action in releasing neurotransmitter. 2. Each flash elicited a phasic postsynaptic response resembling an excitatory junctional potential, apparently due to a presynaptic "spike" in intracellular calcium concentration ([Ca2+]i). 3. When postsynaptic currents were measured under voltage clamp, a Ca2+ cooperativity of approximately 3-4 was inferred from a supralinear dependence of responses on changes in peak [Ca2+]i caused by flashes differing in intensity by 32-46%. 4. A similar Ca2+ cooperativity was inferred from postsynaptic potentials in response to flashes of varying intensity. 5. The time course of transmitter release indicated by flash responses had slightly slower rising and falling phases than excitatory postsynaptic potentials. There was also a slow tail of transmitter release lasting for approximately 200 ms after a flash. 6. This time course was explained quantitatively by simulations of DM-nitrophen photolysis and binding reactions and a model of Ca2+ activation of transmitter release.

PubMed Disclaimer

Cited by

Direct enhancement of presynaptic calcium influx in presynaptic facilitation at Aplysia sensorimotor synapses.
Leal K, Klein M. Leal K, et al. Mol Cell Neurosci. 2009 Jun;41(2):247-57. doi: 10.1016/j.mcn.2009.03.004. Epub 2009 Mar 31. Mol Cell Neurosci. 2009. PMID: 19344767 Free PMC article.
The facilitated probability of quantal secretion within an array of calcium channels of an active zone at the amphibian neuromuscular junction.
Bennett MR, Farnell L, Gibson WG. Bennett MR, et al. Biophys J. 2004 May;86(5):2674-90. doi: 10.1016/S0006-3495(04)74323-4. Biophys J. 2004. PMID: 15111388 Free PMC article.
Presynaptic calcium dynamics and transmitter release evoked by single action potentials at mammalian central synapses.
Sinha SR, Wu LG, Saggau P. Sinha SR, et al. Biophys J. 1997 Feb;72(2 Pt 1):637-51. doi: 10.1016/s0006-3495(97)78702-2. Biophys J. 1997. PMID: 9017193 Free PMC article.
Dual mechanism for presynaptic modulation by axonal metabotropic glutamate receptor at the mouse mossy fibre-CA3 synapse.
Kamiya H, Ozawa S. Kamiya H, et al. J Physiol. 1999 Jul 15;518 ( Pt 2)(Pt 2):497-506. doi: 10.1111/j.1469-7793.1999.0497p.x. J Physiol. 1999. PMID: 10381595 Free PMC article.
Synaptic Secretion and Beyond: Targeting Synapse and Neurotransmitters to Treat Neurodegenerative Diseases.
Wei Z, Wei M, Yang X, Xu Y, Gao S, Ren K. Wei Z, et al. Oxid Med Cell Longev. 2022 Jul 25;2022:9176923. doi: 10.1155/2022/9176923. eCollection 2022. Oxid Med Cell Longev. 2022. PMID: 35923862 Free PMC article. Review.

Ca2+ cooperativity in neurosecretion measured using photolabile Ca2+ chelators - PubMed (original) (raw)