PT  - JOURNAL ARTICLE
AU  - Wu, Ling-Gang
AU  - Westenbroek, Ruth E.
AU  - Borst, J. Gerard G.
AU  - Catterall, William A.
AU  - Sakmann, Bert
TI  - Calcium Channel Types with Distinct Presynaptic Localization Couple Differentially to Transmitter Release in Single Calyx-Type Synapses
AID  - 10.1523/JNEUROSCI.19-02-00726.1999
DP  - 1999 Jan 15
TA  - The Journal of Neuroscience
PG  - 726--736
VI  - 19
IP  - 2
4099  - http://www.jneurosci.org/content/19/2/726.short
4100  - http://www.jneurosci.org/content/19/2/726.full
SO  - J. Neurosci.1999 Jan 15; 19
AB  - We studied how Ca2+ influx through different subtypes of Ca2+ channels couples to release at a calyx-type terminal in the rat medial nucleus of the trapezoid body by simultaneously measuring the presynaptic Ca2+ influx evoked by a single action potential and the EPSC. Application of subtype-specific toxins showed that Ca2+ channels of the P/Q-, N-, and R-type controlled glutamate release at a single terminal. The Ca2+influx through the P/Q-type channels triggered release more effectively than Ca2+ influx through N- or R-type channels. We investigated mechanisms that contributed to these differences in effectiveness. Electrophysiological experiments suggested that individual release sites were controlled by all three subtypes of Ca2+ channels. Immunocytochemical staining indicated, however, that a substantial fraction of N- and R-type channels was located distant from release sites. Although these distant channels contributed to the Ca2+ influx into the terminal, they may not contribute to release. Taken together, the results suggest that the Ca2+ influx into the calyx via N- and R-type channels triggers release less effectively than that via P/Q-type because a substantial fraction of the N- and R-type channels in the calyx is localized distant from release sites.