Presynaptic action potential amplification by voltage-gated Na+ channels in hippocampal mossy fiber boutons Journal Article


Author(s): Engel, Dominique; Jonas, Peter
Article Title: Presynaptic action potential amplification by voltage-gated Na+ channels in hippocampal mossy fiber boutons
Affiliation
Abstract: Action potentials in central neurons are initiated near the axon initial segment, propagate into the axon, and finally invade the presynaptic terminals, where they trigger transmitter release. Voltage-gated Na(+) channels are key determinants of excitability, but Na(+) channel density and properties in axons and presynaptic terminals of cortical neurons have not been examined yet. In hippocampal mossy fiber boutons, which emerge from parent axons en passant, Na(+) channels are very abundant, with an estimated number of approximately 2000 channels per bouton. Presynaptic Na(+) channels show faster inactivation kinetics than somatic channels, suggesting differences between subcellular compartments of the same cell. Computational analysis of action potential propagation in axon-multibouton structures reveals that Na(+) channels in boutons preferentially amplify the presynaptic action potential and enhance Ca(2+) inflow, whereas Na(+) channels in axons control the reliability and speed of propagation. Thus, presynaptic and axonal Na(+) channels contribute differentially to mossy fiber synaptic transmission.
Keywords: Animals; Rats; Calcium/metabolism; Rats, Wistar; Action Potentials/physiology; Organ Culture Techniques; Synaptic Transmission/physiology; Presynaptic Terminals/physiology; Sodium Channels/physiology; Ion Channel Gating/physiology; Calcium Signaling/physiology; Cell Compartmentation/physiology; Synaptic Membranes/physiology; Mossy Fibers, Hippocampal/physiology
Journal Title: Neuron
Volume: 45
Issue 3
ISSN: 0896-6273
Publisher: Elsevier  
Publication Place: United States
Date Published: 2005-01-01
Start Page: 405
End Page: 17
DOI: 10.1016/j.neuron.2004.12.048
Open access: no