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Presynaptic N‐type and P/Q‐type Ca 2+ channels mediating synaptic transmission at the calyx of Held of mice
Author(s) -
Ishikawa Taro,
Kaneko Masahiro,
Shin HeeSup,
Takahashi Tomoyuki
Publication year - 2005
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2005.089912
Subject(s) - calyx , neurotransmission , neuroscience , biology , chemistry , biophysics , physics , anatomy , genetics , receptor
At the nerve terminal, both N‐ and P/Q‐type Ca 2 + channels mediate synaptic transmission, with their relative contribution varying between synapses and with postnatal age. To clarify functional significance of different presynaptic Ca 2 + channel subtypes, we recorded N‐type and P/Q‐type Ca 2 + currents directly from calyces of Held nerve terminals in α 1A ‐subunit‐deficient mice and wild‐type (WT) mice, respectively. The most prominent feature of P/Q‐type Ca 2 + currents was activity‐dependent facilitation, which was absent for N‐type Ca 2 + currents. EPSCs mediated by P/Q‐type Ca 2 + currents showed less depression during high‐frequency stimulation compared with those mediated by N‐type Ca 2 + currents. In addition, the maximal inhibition by the GABA B receptor agonist baclofen was greater for EPSCs mediated by N‐type channels than for those mediated by P/Q‐type channels. These results suggest that the developmental switch of presynaptic Ca 2 + channels from N‐ to P/Q‐type may serve to increase synaptic efficacy at high frequencies of activity, securing high‐fidelity synaptic transmission.