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Updated: Aug 3, 2026
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Methods for Patch Clamp Capacitance Recordings from the Calyx
Published on: July 29, 2007
Postsynaptic Ca2+ influx mediated by three different pathways during synaptic transmission at a calyx-type synapse
J H Bollmann1, F Helmchen, J G Borst
1Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung, D-69120 Heidelberg, Germany.
Summary
Voltage-dependent Ca2+ channels (VDCCs) and NMDA-type (NMDAR) channels are the primary contributors to postsynaptic Ca2+ influx at rat calyx synapses. AMPA-type (AMPAR) channels play a minor role, with distinct temporal and spatial contributions from each pathway.
Area of Science:
- Neuroscience
- Cellular Biology
- Biophysics
Background:
- Synaptic transmission relies on postsynaptic calcium (Ca2+) influx.
- Glutamate receptor (GluR) channels and voltage-dependent Ca2+ channels (VDCCs) are key mediators of Ca2+ influx.
- Understanding the relative contributions of these channels is crucial for deciphering synaptic function.
Purpose of the Study:
- To quantify the contribution of GluR channels and VDCCs to postsynaptic Ca2+ influx at a rat calyx-type synapse.
- To investigate the temporal and spatial dynamics of Ca2+ influx through different channels.
Main Methods:
- Whole-cell recordings in rat brainstem slices.
- Ca2+ flux measurements.
- Electrophysiological recordings and computational simulations.
Main Results:
- A single action potential (AP) evoked a postsynaptic Ca2+ influx of ~3.0 pC.
- VDCCs accounted for ~70% of the Ca2+ influx, NMDARs for up to 30%, and AMPARs for <5%.
- AMPAR-mediated Ca2+ influx was transient and early, while NMDAR influx dominated later; VDCC influx was more widespread.
Conclusions:
- VDCCs and NMDARs are the major pathways for postsynaptic Ca2+ influx at this synapse.
- The distinct temporal and spatial profiles of Ca2+ influx suggest activation of different intracellular targets.
- This differential activation could play a role in modulating synaptic plasticity and function.
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