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Presynaptic Calcium Channel Open Probability and Changes in Calcium Influx Throughout the Action Potential Determined
Matthew S Scarnati1,2, Stephen G Clarke1,3, Zhiping P Pang2
1Department of Cell Biology and Neuroscience, Rutgers University Piscataway, Piscataway, NJ, United States.
Frontiers in Synaptic Neuroscience
|May 20, 2020
Summary
Action potential shape significantly impacts calcium influx at nerve terminals, influencing neurotransmitter release. Optimized action potential-like stimuli maximize calcium channel activation for efficient signaling.
Area of Science:
- Neuroscience
- Cellular Biology
- Neurophysiology
Background:
- Action potentials trigger neurotransmitter release by activating voltage-gated calcium channels.
- Changes in action potential shape during propagation affect calcium entry and neurotransmitter release.
- Understanding presynaptic calcium channel dynamics is crucial for neurotransmission.
Purpose of the Study:
- To investigate how action potential shape and amplitude influence calcium influx at presynaptic nerve terminals.
- To compare calcium channel activation by standard voltage jumps versus action potential-like stimuli.
- To determine the temporal activation of calcium channels during an action potential.
Main Methods:
- Used amplitude and area-matched stimuli to mimic action potentials.
- Tested various action potential-like stimuli with differing rise and decay times.
- Quantified calcium channel activation during different phases of the action potential.
Main Results:
- Action potential-like stimuli elicit different calcium entry patterns compared to standard voltage jumps.
- Stimuli matching physiological action potential rise and decay times optimize calcium channel response.
- Only ~20% of calcium channels open during the depolarizing phase; peak activation occurs near 0 mV.
- Late-activating channels contribute to higher local calcium concentrations, increasing neurotransmitter release probability.
Conclusions:
- Action potential shape is a critical determinant of presynaptic calcium influx and neurotransmitter release.
- Presynaptic calcium channel activation is a dynamic process throughout the action potential.
- Understanding the interplay between calcium channel open probability and local calcium concentration is essential for comprehending neurotransmission.
Keywords:
action potentialcalcium channelslocal calcium concentrationmicrodomainsnanodomainsneurotransmitter releaseopen probabilitypresynapticMore Related Videos
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