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Differential triggering of spontaneous glutamate release by P/Q-, N- and R-type Ca2+ channels

Nature Neuroscience volume 16, pages 1754–1763 (2013)Cite this article

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Abstract

The role of voltage-gated Ca2+ channels (VGCCs) in spontaneous miniature neurotransmitter release is incompletely understood. We found that stochastic opening of P/Q-, N- and R-type VGCCs accounts for ∼50% of all spontaneous glutamate release at rat cultured hippocampal synapses, and that R-type channels have a far greater role in spontaneous than in action potential–evoked exocytosis. VGCC-dependent miniature neurotransmitter release (minis) showed similar sensitivity to presynaptic Ca2+ chelation as evoked release, arguing for direct triggering of spontaneous release by transient spatially localized Ca2+ domains. Experimentally constrained three-dimensional diffusion modeling of Ca2+ influx–exocytosis coupling was consistent with clustered distribution of VGCCs in the active zone of small hippocampal synapses and revealed that spontaneous VGCCs openings can account for the experimentally observed VGCC-dependent minis, although single channel openings triggered release with low probability. Uncorrelated stochastic VGCC opening is therefore a major trigger for spontaneous glutamate release, with differential roles for distinct channel subtypes.

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Figure 1: Differential triggering of spontaneous excitatory neurotransmission by P/Q-, N- and R-type Ca2+ channels.
Figure 2: Relative contributions of P/Q-, N- and R-type VGCCs to presynaptic Ca2+ dynamics assessed with fast Ca2+ fluorescence imaging.
Figure 3: Differential effects of fast (BAPTA) and slow (EGTA) exogenous Ca2+ buffers on VGCC-dependent minis.
Figure 4: FM dye imaging of action potential–evoked exocytosis reveals similar sensitivity of evoked and VGCC-dependent miniature release to presynaptic Ca2+ chelation.
Figure 5: Estimation of the numbers of P/Q-, N- and R-type VGCCs in an average presynaptic bouton.
Figure 6: Modeling action potential–evoked release in small hippocampal synapses.
Figure 7: Modeling VGCC-dependent glutamate miniature release.

References

  1. Sutton, M.A., Wall, N.R., Aakalu, G.N. & Schuman, E.M. Regulation of dendritic protein synthesis by miniature synaptic events. Science 304, 1979–1983 (2004).

    Article  CAS  PubMed  Google Scholar 

  2. McKinney, R.A., Capogna, M., Durr, R., Gahwiler, B.H. & Thompson, S.M. Miniature synaptic events maintain dendritic spines via AMPA receptor activation. Nat. Neurosci. 2, 44–49 (1999).

    Article  CAS  PubMed  Google Scholar 

  3. Groffen, A.J. et al. Doc2b is a high-affinity Ca2+ sensor for spontaneous neurotransmitter release. Science 327, 1614–1618 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  4. Xu, J., Pang, Z.P., Shin, O.H. & Sudhof, T.C. Synaptotagmin-1 functions as a Ca2+ sensor for spontaneous release. Nat. Neurosci. 12, 759–766 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  5. Eggermann, E., Bucurenciu, I., Goswami, S.P. & Jonas, P. Nanodomain coupling between Ca(2+) channels and sensors of exocytosis at fast mammalian synapses. Nat. Rev. Neurosci. 13, 7–21 (2012).

    Article  CAS  Google Scholar 

  6. Williams, C. et al. Coactivation of multiple tightly coupled calcium channels triggers spontaneous release of GABA. Nat. Neurosci. 15, 1195–1197 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  7. Goswami, S.P., Bucurenciu, I. & Jonas, P. Miniature IPSCs in hippocampal granule cells are triggered by voltage-gated Ca2+ channels via microdomain coupling. J. Neurosci. 32, 14294–14304 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Vyleta, N.P. & Smith, S.M. Spontaneous glutamate release is independent of calcium influx and tonically activated by the calcium-sensing receptor. J. Neurosci. 31, 4593–4606 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  9. Scanziani, M., Capogna, M., Gahwiler, B.H. & Thompson, S.M. Presynaptic inhibition of miniature excitatory synaptic currents by baclofen and adenosine in the hippocampus. Neuron 9, 919–927 (1992).

    Article  CAS  PubMed  Google Scholar 

  10. Wu, L.G. & Saggau, P. Pharmacological identification of two types of presynaptic voltage-dependent calcium channels at CA3–CA1 synapses of the hippocampus. J. Neurosci. 14, 5613–5622 (1994).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  11. Sheng, J. et al. Calcium-channel number critically influences synaptic strength and plasticity at the active zone. Nat. Neurosci. 15, 998–1006 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  12. Li, L., Bischofberger, J. & Jonas, P. Differential gating and recruitment of P/Q-, N-, and R-type Ca2+ channels in hippocampal mossy fiber boutons. J. Neurosci. 27, 13420–13429 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  13. Reid, C.A., Bekkers, J.M. & Clements, J.D. N- and P/Q-type Ca2+ channels mediate transmitter release with a similar cooperativity at rat hippocampal autapses. J. Neurosci. 18, 2849–2855 (1998).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  14. Mintz, I.M., Sabatini, B.L. & Regehr, W.G. Calcium control of transmitter release at a cerebellar synapse. Neuron 15, 675–688 (1995).

    Article  CAS  PubMed  Google Scholar 

  15. Holderith, N. et al. Release probability of hippocampal glutamatergic terminals scales with the size of the active zone. Nat. Neurosci. 15, 988–997 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  16. Soong, T.W. et al. Structure and functional expression of a member of the low voltage-activated calcium channel family. Science 260, 1133–1136 (1993).

    Article  CAS  PubMed  Google Scholar 

  17. Regehr, W.G. & Atluri, P.P. Calcium transients in cerebellar granule cell presynaptic terminals. Biophys. J. 68, 2156–2170 (1995).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  18. Xu, B. et al. Calcium signaling is involved in cadmium-induced neuronal apoptosis via induction of reactive oxygen species and activation of MAPK/mTOR network. PLoS ONE 6, e19052 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  19. Lou, X., Scheuss, V. & Schneggenburger, R. Allosteric modulation of the presynaptic Ca2+ sensor for vesicle fusion. Nature 435, 497–501 (2005).

    Article  CAS  PubMed  Google Scholar 

  20. Neher, E. Usefulness and limitations of linear approximations to the understanding of Ca2+ signals. Cell Calcium 24, 345–357 (1998).

    Article  CAS  PubMed  Google Scholar 

  21. Atluri, P.P. & Regehr, W.G. Determinants of the time course of facilitation at the granule cell to Purkinje cell synapse. J. Neurosci. 16, 5661–5671 (1996).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  22. Ohana, O. & Sakmann, B. Transmitter release modulation in nerve terminals of rat neocortical pyramidal cells by intracellular calcium buffers. J. Physiol. (Lond.) 513, 135–148 (1998).

    Article  CAS  Google Scholar 

  23. Bucurenciu, I., Kulik, A., Schwaller, B., Frotscher, M. & Jonas, P. Nanodomain coupling between Ca2+ channels and Ca2+ sensors promotes fast and efficient transmitter release at a cortical GABAergic synapse. Neuron 57, 536–545 (2008).

    Article  CAS  PubMed  Google Scholar 

  24. Murthy, V.N., Schikorski, T., Stevens, C.F. & Zhu, Y. Inactivity produces increases in neurotransmitter release and synapse size. Neuron 32, 673–682 (2001).

    Article  CAS  PubMed  Google Scholar 

  25. Ermolyuk, Y.S. et al. Independent regulation of basal neurotransmitter release efficacy by variable Ca2+ influx and bouton size at small central synapses. PLoS Biol. 10, e1001396 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  26. Gaffield, M.A. & Betz, W.J. Imaging synaptic vesicle exocytosis and endocytosis with FM dyes. Nat. Protoc. 1, 2916–2921 (2006).

    Article  CAS  PubMed  Google Scholar 

  27. Hoppa, M.B., Lana, B., Margas, W., Dolphin, A.C. & Ryan, T.A. Alpha2delta expression sets presynaptic calcium channel abundance and release probability. Nature 486, 122–125 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  28. Meinrenken, C.J., Borst, J.G. & Sakmann, B. Calcium secretion coupling at calyx of held governed by nonuniform channel-vesicle topography. J. Neurosci. 22, 1648–1667 (2002).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  29. Scimemi, A. & Diamond, J.S. The number and organization of Ca2+ channels in the active zone shapes neurotransmitter release from Schaffer collateral synapses. J. Neurosci. 32, 18157–18176 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  30. Ariel, P. & Ryan, T.A. Optical mapping of release properties in synapses. Front. Neural Circuits 4, 18 (2010).

    PubMed  PubMed Central  Google Scholar 

  31. Rozov, A., Burnashev, N., Sakmann, B. & Neher, E. Transmitter release modulation by intracellular Ca2+ buffers in facilitating and depressing nerve terminals of pyramidal cells in layer 2/3 of the rat neocortex indicates a target cell-specific difference in presynaptic calcium dynamics. J. Physiol. (Lond.) 531, 807–826 (2001).

    Article  CAS  Google Scholar 

  32. Schikorski, T. & Stevens, C.F. Quantitative ultrastructural analysis of hippocampal excitatory synapses. J. Neurosci. 17, 5858–5867 (1997).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  33. Novak, P. et al. Nanoscale-targeted patch-clamp recordings of functional presynaptic ion channels. Neuron 79, 1067–1077 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  34. Shepherd, G.M. & Harris, K.M. Three-dimensional structure and composition of CA3→CA1 axons in rat hippocampal slices: implications for presynaptic connectivity and compartmentalization. J. Neurosci. 18, 8300–8310 (1998).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  35. Siksou, L. et al. Three-dimensional architecture of presynaptic terminal cytomatrix. J. Neurosci. 27, 6868–6877 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  36. Bucurenciu, I., Bischofberger, J. & Jonas, P. A small number of open Ca2+ channels trigger transmitter release at a central GABAergic synapse. Nat. Neurosci. 13, 19–21 (2010).

    Article  CAS  PubMed  Google Scholar 

  37. Matveev, V., Bertram, R. & Sherman, A. Calcium cooperativity of exocytosis as a measure of Ca2+ channel domain overlap. Brain Res. 1398, 126–138 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  38. Weber, A.M. et al. N-type Ca2+ channels carry the largest current: implications for nanodomains and transmitter release. Nat. Neurosci. 13, 1348–1350 (2010).

    Article  CAS  PubMed  Google Scholar 

  39. Atasoy, D. et al. Spontaneous and evoked glutamate release activates two populations of NMDA receptors with limited overlap. J. Neurosci. 28, 10151–10166 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  40. Geppert, M. et al. Synaptotagmin I: a major Ca2+ sensor for transmitter release at a central synapse. Cell 79, 717–727 (1994).

    Article  CAS  PubMed  Google Scholar 

  41. Murthy, V.N. & Stevens, C.F. Reversal of synaptic vesicle docking at central synapses. Nat. Neurosci. 2, 503–507 (1999).

    Article  CAS  PubMed  Google Scholar 

  42. Sharma, G. & Vijayaraghavan, S. Modulation of presynaptic store calcium induces release of glutamate and postsynaptic firing. Neuron 38, 929–939 (2003).

    Article  CAS  PubMed  Google Scholar 

  43. Emptage, N.J., Reid, C.A. & Fine, A. Calcium stores in hippocampal synaptic boutons mediate short-term plasticity, store-operated Ca2+ entry, and spontaneous transmitter release. Neuron 29, 197–208 (2001).

    Article  CAS  PubMed  Google Scholar 

  44. Mochida, S. et al. Requirement for the synaptic protein interaction site for reconstitution of synaptic transmission by P/Q-type calcium channels. Proc. Natl. Acad. Sci. USA 100, 2819–2824 (2003).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  45. Kaeser, P.S. et al. RIM proteins tether Ca2+ channels to presynaptic active zones via a direct PDZ-domain interaction. Cell 144, 282–295 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  46. Bao, J., Li, J.J. & Perl, E.R. Differences in Ca2+ channels governing generation of miniature and evoked excitatory synaptic currents in spinal laminae I and II. J. Neurosci. 18, 8740–8750 (1998).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  47. Pavlov, I., Scimemi, A., Savtchenko, L., Kullmann, D.M. & Walker, M.C. Ih-mediated depolarization enhances the temporal precision of neuronal integration. Nat. Commun. 2, 199 (2011).

    Article  PubMed  CAS  Google Scholar 

  48. Banke, T.G. & McBain, C.J. GABAergic input onto CA3 hippocampal interneurons remains shunting throughout development. J. Neurosci. 26, 11720–11725 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  49. Ruiz, A., Campanac, E., Scott, R.S., Rusakov, D.A. & Kullmann, D.M. Presynaptic GABAA receptors enhance transmission and LTP induction at hippocampal mossy fiber synapses. Nat. Neurosci. 13, 431–438 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  50. Alle, H. & Geiger, J.R. Analog signalling in mammalian cortical axons. Curr. Opin. Neurobiol. 18, 314–320 (2008).

    Article  CAS  PubMed  Google Scholar 

  51. Dreyfus, F.M. et al. Selective T-type calcium channel block in thalamic neurons reveals channel redundancy and physiological impact of I(T)window. J. Neurosci. 30, 99–109 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  52. Maravall, M., Mainen, Z.F., Sabatini, B.L. & Svoboda, K. Estimating intracellular calcium concentrations and buffering without wavelength ratioing. Biophys. J. 78, 2655–2667 (2000).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  53. Benson, D.L., Watkins, F.H., Steward, O. & Banker, G. Characterization of GABAergic neurons in hippocampal cell cultures. J. Neurocytol. 23, 279–295 (1994).

    Article  CAS  PubMed  Google Scholar 

  54. Hines, M.L. & Carnevale, N.T. The NEURON simulation environment. Neural Comput. 9, 1179–1209 (1997).

    Article  CAS  PubMed  Google Scholar 

  55. Sasaki, T., Matsuki, N. & Ikegaya, Y. Action-potential modulation during axonal conduction. Science 331, 599–601 (2011).

    Article  CAS  PubMed  Google Scholar 

  56. Borst, J.G., Helmchen, F. & Sakmann, B. Pre- and postsynaptic whole-cell recordings in the medial nucleus of the trapezoid body of the rat. J. Physiol. (Lond.) 489, 825–840 (1995).

    Article  CAS  Google Scholar 

  57. Scott, R. & Rusakov, D.A. Main determinants of presynaptic Ca2+ dynamics at individual mossy fiber-CA3 pyramidal cell synapses. J. Neurosci. 26, 7071–7081 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  58. Faas, G.C., Raghavachari, S., Lisman, J.E. & Mody, I. Calmodulin as a direct detector of Ca2+ signals. Nat. Neurosci. 14, 301–304 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  59. Nägerl, U.V., Novo, D., Mody, I. & Vergara, J.L. Binding kinetics of calbindin-D(28k) determined by flash photolysis of caged Ca2+. Biophys. J. 79, 3009–3018 (2000).

    Article  PubMed  PubMed Central  Google Scholar 

  60. Xia, Z. & Storm, D.R. The role of calmodulin as a signal integrator for synaptic plasticity. Nat. Rev. Neurosci. 6, 267–276 (2005).

    Article  CAS  PubMed  Google Scholar 

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Acknowledgements

We are grateful to L. Savtchenko for help with stochastic VGCC modeling, to P. Volynsky for help with Monte-Carlo simulations of VGCC distributions in the active zone, to M. Cano for help with neuronal cultures, to V. Uebele (Merck) for the gift of TTA-P2, and to Y. Ushkaryov, D. Rusakov, C. Henneberger and M. Walker for critical reading of the manuscript. The study was supported by the Medical Research Council, the Wellcome Trust, the Biotechnology and Biological Sciences Research Council, the German Research Foundation, the Brain Research Trust, the European Research Council, the Special Trustees of the University College London Hospitals National Health Service Foundation Trust, Epilepsy Research UK, and The Worshipful Company of Pewterers.

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Author notes

  1. Rainer Surges

    Present address: Present address: Department of Epileptology, University Clinics Bonn, Bonn, Germany.,

  2. Yaroslav S Ermolyuk, Felicity G Alder and Rainer Surges: These authors contributed equally to this work.

Authors and Affiliations

  1. University College London Institute of Neurology, University College London, London, UK

    Yaroslav S Ermolyuk, Felicity G Alder, Rainer Surges, Ivan Y Pavlov, Dimitri M Kullmann & Kirill E Volynski

  2. Department of Computer Science, University of Warwick, Coventry, UK

    Yulia Timofeeva

  3. Centre for Complexity Science, University of Warwick, Coventry, UK

    Yulia Timofeeva

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  1. Yaroslav S Ermolyuk
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Contributions

Y.S.E., F.G.A., R.S. and I.Y.P. performed the experiments. Y.S.E., F.G.A., R.S., I.Y.P. and K.E.V. analyzed the data. Y.T. and K.E.V. performed the computational modeling. D.M.K. and K.E.V. conceived and designed the experiments. D.M.K., Y.T. and K.E.V. wrote the paper.

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Correspondence to Kirill E Volynski.

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Integrated supplementary information

Supplementary Figure 1 Membrane depolarization with elevated extracellular leads to an increase in VGCC-dependent miniature release.

(a, b) Time course of mEPSC frequency changes after application of 20 mM followed by simultaneous blockade of P/Q-, N-, and R-type VGCCs with ω-Aga, ω-Ctx and SNX. (a) mEPSC traces from a representative experiment and (b) average time course in N=7 cells (mean ± s.e.m). The integration periods used to determine the effects of 20mM and VGCC blockers on average mEPSC frequency are indicated by black circles. * P < 0.05, Wilcoxon signed rank test for paired data.

Supplementary Figure 2 Action potential-evoked currents mediated by single P/Q-, N-, and R-type VGCCs simulated using the six-state VGCC gating model.

Results of 20 representative simulations for each channel subtype (blue, P/Q-; green, N-; and brown, R-type channels). Action potential waveform is shown on the top left. Average current time courses including failures are shown at bottom (bold traces). The probability that an individual channel opens during an action potential (estimated from 500 simulations) was: Popen_P/Q = 0.50, Popen_N = 0.40, and Popen_R = 0.32.

Supplementary Figure 3 Clustered model, additional analysis: VGCC cooperativity in triggering action potential-evoked release varies with docked vesicle-VGCC cluster distance.

(a) Detailed schematic representation of the active zone for the Clustered model illustrated in Fig. 6c. VGCC positions, subtypes, and their open or closed status during the simulated action potential are specified as indicated in the insert on the right. In this model implementation 12 out of 32 VGCCs opened during the action potential (5 channels opened in the cluster located to the left side of the active zone and 7 channels opened in the cluster located to the right side of the active zone). (b) Spatiotemporal profile during the simulated action potential within a 5 nm thick plane immediately above the active zone. Top, action potential waveform; bottom, color-coded map at different time points as indicated. Note that at the late action potential repolarization stage when Ca2+ currents through individual VGCCs are maximal (i.e. at 0.45 ms and 0.6 ms) Ca2+ influx in each channel cluster is mediated only by 1 or 2 VGCCs. For example, the red circle in (a) and (b) highlights two VGCCs (of N-type) that contribute most of the action potential-evoked Ca2+ current in the left channel cluster. Scale bar 50 nm. (c, d) To determine the relative contributions of the two channels highlighted in (a) and (b) to triggering release of vesicles V1 - V4 we either selectively switched them off (c, top) or left them active and switched off all other channels (c, bottom). (d) Average concentration transients at vesicular release sensors and corresponding vesicle fusion probabilities Pv (shown above) for each vesicle in the active zone. Black traces, original control simulation; red traces, the two highlighted channels 'switched off', blue traces, all but the two highlighted channels 'switched off'. The results of the above simulations show that: (1) The two highlighted channels contributed most of the action potential-evoked concentration transients at release sensors of vesicle V1, which was located in the immediate vicinity of these two VGCCs (30 and 40 nm). Switching these two channels off led to a ∼22-fold reduction of the vesicle fusion probability Pv, (from 0.22 to 0.01). In contrast, switching off all other VGCCs in the active zone led to only a 2.4-fold reduction in Pv of Vesicle V1. Thus, in this model realization fusion of vesicle V1 is mainly controlled by the two highlighted channels. (2) The two highlighted channels had a minimal effect on concentration transients at the release sensors of vesicle V4, and as a consequence on Pv for this vesicle, which was located close (~30 nm) to the other VGCC cluster. This illustrates that action potential-evoked fusion of vesicles located in the immediate vicinity of VGCC clusters is mainly controlled by channels from the nearest cluster. (3) Finally, for vesicles that were further away from the VGCC clusters, and therefore had lower Pv (vesicles V2 and V4), action potential-evoked fusion was jointly controlled by VGCCs from both clusters.

Supplementary Figure 4 Dependency of stochastic VGCC openings on Vrest.

Representative traces of Ca2+ currents simulated using the six-state VGCC gating model at different Vrest in a typical active zone containing 15 P/Q-, 16 N-, and 2 R-type VGCCs. These simulations (in total 200 s for each Vrest value) showed that within the physiological Vrest range (from –55 to –80 mV) the probability of coincident opening of more than one channel in the active zone is lower than 0.002.

Supplementary Figure 5 Modeling of miniature glutamate release triggered by Ca2+ release from intracellular stores. Comparison of 0.5 mM BAPTA and 5 mM EGTA effects.

(a, b) To model the small (∼1 μM) elevations of presynaptic from = 50 nM, as might occur during Ca2+ release from intracellular stores (e.g. refs. 42,43), we used a single-compartment model of presynaptic Ca2+ dynamics (see Online Methods for details). (a) Ca2+ influx into the cytosol from the stores was approximated by a Gaussian function with a maximal rate = 1 μM ms-1 (~100 fold slower than that during an action potential) and with a characteristic duration σ = 2 s. (b) Resulting global presynaptic concentration transients predicted by the non-stationary model in 'Control' conditions (black trace) and in the presence of 0.5 mM BAPTA (red trace) and 5 mM EGTA (blue trace). Note that, in contrast to 5 mM EGTA, 0.5 mM BAPTA had only minor effect on the presynaptic transient. (c) Vesicular release rates and (d) fusion probabilities Pv, corresponding to transients shown in (b). These were calculated using the same allosteric model as used to model VGCC-dependent glutamate release (Fig. 6a). Consistent with the effect of Ca2+ chelators on the global presynaptic transients, 5 mM EGTA was much more efficient in inhibiting of store-mediated miniature release (by ~88%) than 0.5 mM BAPTA (by ~13%).

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Ermolyuk, Y., Alder, F., Surges, R. et al. Differential triggering of spontaneous glutamate release by P/Q-, N- and R-type Ca2+ channels. Nat Neurosci 16, 1754–1763 (2013). https://doi.org/10.1038/nn.3563

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