Differential gating and recruitment of P/Q-, N-, and R-type Ca(2+) channels in hippocampal mossy fiber boutons

Li L, Bischofberger J, Jonas PM. 2007. Differential gating and recruitment of P/Q-, N-, and R-type Ca(2+) channels in hippocampal mossy fiber boutons. Journal of Neuroscience. 27(49), 13420–9.

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Journal Article | Published
Author
Li, Liyi; Bischofberger, Josef; Jonas, Peter MIST Austria
Abstract
Voltage-gated Ca2+ channels in presynaptic terminals initiate the Ca2+ inflow necessary for transmitter release. At a variety of synapses, multiple Ca2+ channel subtypes are involved in synaptic transmission and plasticity. However, it is unknown whether presynaptic Ca2+ channels differ in gating properties and whether they are differentially activated by action potentials or subthreshold voltage signals. We examined Ca2+ channels in hippocampal mossy fiber boutons (MFBs) by presynaptic recording, using the selective blockers omega-agatoxin IVa, omega-conotoxin GVIa, and SNX-482 to separate P/Q-, N-, and R-type components. Nonstationary fluctuation analysis combined with blocker application revealed a single MFB contained on average approximately 2000 channels, with 66% P/Q-, 26% N-, and 8% R-type channels. Whereas both P/Q-type and N-type Ca2+ channels showed high activation threshold and rapid activation and deactivation, R-type Ca2+ channels had a lower activation threshold and slower gating kinetics. To determine the efficacy of activation of different Ca2+ channel subtypes by physiologically relevant voltage waveforms, a six-state gating model reproducing the experimental observations was developed. Action potentials activated P/Q-type Ca2+ channels with high efficacy, whereas N- and R-type channels were activated less efficiently. Action potential broadening selectively recruited N- and R-type channels, leading to an equalization of the efficacy of channel activation. In contrast, subthreshold presynaptic events activated R-type channels more efficiently than P/Q- or N-type channels. In conclusion, single MFBs coexpress multiple types of Ca2+ channels, which are activated differentially by subthreshold and suprathreshold presynaptic voltage signals.
Publishing Year
Date Published
2007-01-01
Journal Title
Journal of Neuroscience
Volume
27
Issue
49
Page
13420 - 9
IST-REx-ID

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Li L, Bischofberger J, Jonas PM. Differential gating and recruitment of P/Q-, N-, and R-type Ca(2+) channels in hippocampal mossy fiber boutons. Journal of Neuroscience. 2007;27(49):13420-13429. doi:10.1523/JNEUROSCI.1709-07.2007
Li, L., Bischofberger, J., & Jonas, P. M. (2007). Differential gating and recruitment of P/Q-, N-, and R-type Ca(2+) channels in hippocampal mossy fiber boutons. Journal of Neuroscience. Society for Neuroscience. https://doi.org/10.1523/JNEUROSCI.1709-07.2007
Li, Liyi, Josef Bischofberger, and Peter M Jonas. “Differential Gating and Recruitment of P/Q-, N-, and R-Type Ca(2+) Channels in Hippocampal Mossy Fiber Boutons.” Journal of Neuroscience. Society for Neuroscience, 2007. https://doi.org/10.1523/JNEUROSCI.1709-07.2007.
L. Li, J. Bischofberger, and P. M. Jonas, “Differential gating and recruitment of P/Q-, N-, and R-type Ca(2+) channels in hippocampal mossy fiber boutons,” Journal of Neuroscience, vol. 27, no. 49. Society for Neuroscience, pp. 13420–9, 2007.
Li L, Bischofberger J, Jonas PM. 2007. Differential gating and recruitment of P/Q-, N-, and R-type Ca(2+) channels in hippocampal mossy fiber boutons. Journal of Neuroscience. 27(49), 13420–9.
Li, Liyi, et al. “Differential Gating and Recruitment of P/Q-, N-, and R-Type Ca(2+) Channels in Hippocampal Mossy Fiber Boutons.” Journal of Neuroscience, vol. 27, no. 49, Society for Neuroscience, 2007, pp. 13420–29, doi:10.1523/JNEUROSCI.1709-07.2007.

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