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

L. Li, J. Bischofberger, P.M. Jonas, Journal of Neuroscience 27 (2007) 13420–9.

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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, 27(49), 13420–13429. 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 27, no. 49 (2007): 13420–29. 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, 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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