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PubMed · 9539805

R-type Ca2+ currents evoke transmitter release at a rat central synapse.

L G Wu·J G Borst·B Sakmann
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Abstract

Voltage-dependent Ca2+ currents evoke synaptic transmitter release. Of six types of Ca2+ channels, L-, N-, P-, Q-, R-, and T-type, only N- and P/Q-type channels have been pharmacologically identified to mediate action-potential-evoked transmitter release in the mammalian central nervous system. We tested whether Ca2+ channels other than N- and P/Q-type control transmitter release in a calyx-type synapse of the rat medial nucleus of the trapezoid body. Simultaneous recordings of presynaptic Ca2+ influx and the excitatory postsynaptic current evoked by a single action potential were made at single synapses. The R-type channel, a high-voltage-activated Ca2+ channel resistant to L-, N-, and P/Q-type channel blockers, contributed 26% of the total Ca2+ influx during a presynaptic action potential. This Ca2+ current evoked transmitter release sufficiently large to initiate an action potential in the postsynaptic neuron. The R-type current controlled release with a lower efficacy than other types of Ca2+ currents. Activation of metabotropic glutamate receptors and gamma-aminobutyric acid type B receptors inhibited the R-type current. Because a significant fraction of presynaptic Ca2+ channels remains unidentified in many other central synapses, the R-type current also could contribute to evoked transmitter release in these synapses.

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Action PotentialsAnimalsBaclofenBrain StemCadmium ChlorideCalcium Channel BlockersCalcium ChannelsElectric StimulationEvoked PotentialsIn Vitro TechniquesNeuronsNickelNifedipineNimodipinePatch-Clamp TechniquesPeptidesRatsRats, WistarReceptors, GABA-BReceptors, Metabotropic GlutamateSpider VenomsSynapsesomega-Agatoxin IVAomega-ConotoxinsJournal ArticleResearch Support, Non-U.S. Gov't

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BibTeXRIS

L G Wu, J G Borst, B Sakmann. 1998-04-14. R-type Ca2+ currents evoke transmitter release at a rat central synapse.. https://doi.org/10.1073/pnas.95.8.4720

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