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Sodium channel inactivation: molecular determinants and modulation
1Psychologisches Institut, University of Kiel, Hermann-Rodewald-Strasse 5, D-24118 Kiel, Germany. w.ulbricht@physiologie.uni-kiel.de
Physiological Reviews
|September 27, 2005
Summary
Voltage-gated sodium channels exhibit fast and slow inactivation, distinct processes affecting channel function. Fast inactivation, involving a pore lid, is well-understood, while slow inactivation mechanisms remain unclear.
Area of Science:
- Neuroscience
- Molecular Biology
- Biophysics
Background:
- Voltage-gated sodium channels control neuronal excitability.
- Channel inactivation prevents reopening after depolarization.
- Two types exist: fast (milliseconds) and slow (seconds) inactivation.
Purpose of the Study:
- To differentiate the mechanisms of fast and slow sodium channel inactivation.
- To elucidate the molecular basis of these inactivation processes.
Main Methods:
- Comparative analysis of fast and slow inactivation mechanisms.
- Investigation of molecular locations and conformational changes.
- Examination of modulating factors like chemical agents, toxins, and beta-subunits.
- Analysis of point mutations in hereditary diseases.
Main Results:
- Fast inactivation occurs at the cytoplasmic pore opening, potentially via a hinged lid.
- Slow inactivation involves conformational changes in other channel parts.
- Fast inactivation is sensitive to chemical agents, toxins, enzymes, and beta-subunits.
- Molecular basis of fast inactivation is relatively well-characterized.
Conclusions:
- Fast and slow inactivation are mechanistically distinct processes.
- The molecular underpinnings of fast inactivation are largely elucidated.
- Further research is needed to understand the mechanisms of slow inactivation.