Ca(2+) channels and transmitter release at the active zone
Ralf Schneggenburger1, Yunyun Han, Olexiy Kochubey
1Laboratory of Synaptic Mechanisms, Brain-Mind Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland. ralf.schneggenburger@epfl.ch
Cell Calcium
|June 12, 2012
Summary
Calcium (Ca2+) influx triggers fast neuronal communication. Studies on the calyx of Held synapse reveal multiple Ca2+ channels control vesicle release, distinguishing fast and slow release pools.
Area of Science:
- Neuroscience
- Cell Biology
- Biophysics
Background:
- Neuronal communication relies on Ca(2+)-dependent transmitter release at specialized active zones.
- These zones contain voltage-gated Ca(2+) channels and machinery for vesicle fusion.
- Direct ultrastructural localization of Ca(2+) channels at CNS synapses remains challenging.
Purpose of the Study:
- To investigate the coupling between Ca(2+) channels and vesicle release at the presynaptic terminal.
- To understand the functional relationship between presynaptic Ca(2+) current and neurotransmitter release kinetics.
Main Methods:
- Functional experiments analyzing presynaptic Ca(2+) current and neurotransmitter release.
- Kinetic analysis of release in response to step-like depolarizations at the calyx of Held synapse.
- Utilizing large and accessible synapses for detailed electrophysiological studies.
Main Results:
- Log-log plots indicate multiple Ca(2+) channels regulate single vesicle release.
- Kinetic analysis revealed fast-releasable (FRP) and slow-releasable (SRP) vesicle pools.
- The 'positional' model suggests differential proximity of vesicles to Ca(2+) channels.
Conclusions:
- Ca(2+) channel proximity influences vesicle release kinetics.
- Multivesicular release and membrane clearance are critical for interpreting release data.
- Kinetic analysis of transmitter release offers insights into molecular physiology of synaptic transmission.
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