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Updated: Sep 20, 2025
08:16
Optogenetic Activation of Afferent Pathways in Brain Slices and Modulation of Responses by Volatile Anesthetics
Published on: July 23, 2020
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Volatile anaesthetics modulate voltage-gated sodium channel function at a site critical for gating
Biorxiv : the Preprint Server for Biology
|November 22, 2024
Summary
Volatile anesthetics (VAs) bind to voltage-gated sodium channels (VGSCs), reducing neuronal excitability. This study reveals the first atomic structure of a VA bound to a VGSC, defining a novel binding site and mechanism of action.
Area of Science:
- Neuroscience
- Structural Biology
- Pharmacology
Background:
- Voltage-gated sodium channels (VGSCs) are crucial for neuronal excitability and synaptic transmission.
- Volatile anesthetics (VAs) are known to target VGSCs, but the precise binding sites and mechanisms remain incompletely understood.
Purpose of the Study:
- To elucidate the structural basis of volatile anesthetic interactions with voltage-gated sodium channels.
- To identify the specific binding site and understand the functional consequences of volatile anesthetic binding to VGSCs.
Main Methods:
- X-ray crystallography was employed to determine the atomic-resolution structure of a volatile anesthetic bound to a prokaryotic VGSC (NavMs).
- Structure-function analysis involved site-directed mutagenesis of conserved residues within the identified binding pocket.
- Electrophysiological recordings were used to assess the functional impact of mutations and anesthetic binding on channel activity.
Main Results:
- The first atomic-resolution structure of sevoflurane bound to a VGSC (NavMs) was determined, revealing a binding site within an intramembranous hydrophobic pocket.
- A conserved tyrosine residue within this pocket was identified as critical for channel gating and sevoflurane binding.
- Mutating this tyrosine to alanine abolished sevoflurane binding and the characteristic hyperpolarizing shift in steady-state inactivation, selectively reducing neuronal excitability.
- Evidence suggests similar binding sites and mechanisms are conserved in human VGSC isoforms.
Conclusions:
- This study defines the first volatile anesthetic binding site within a voltage-gated sodium channel.
- A membrane-mediated access pathway facilitates anesthetic binding, leading to negative modulation of channel function.
- These findings provide a molecular basis for the general anesthetic-induced reduction in neuronal activity and synaptic transmission.
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