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The mammalian nodal action potential: new data bring new perspectives
Geoffrey R Tanner1,2, Anastasios V Tzingounis1,2
1Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut.
The classic Hodgkin-Huxley model explains action potential (AP) repolarization using voltage-gated potassium channels. However, recent evidence suggests mammalian axons primarily use leak potassium channels (K2P) for AP repolarization.
Area of Science:
- Neuroscience
- Cellular Physiology
- Biophysics
Background:
- The Hodgkin-Huxley model, based on the squid giant axon (SGA), is the traditional basis for teaching action potential (AP) dynamics.
- This model posits that delayed-rectifier voltage-gated potassium channels mediate AP repolarization and afterhyperpolarization.
- Recent evidence indicates this model may not fully represent mammalian axonal physiology, particularly regarding AP repolarization mechanisms.
Conclusions:
- The mechanisms of action potential repolarization differ significantly between invertebrates and mammals.
- Leak potassium channels (K2P) play a crucial, potentially dominant, role in mammalian axonal repolarization.
- Physiology education should be updated to include these updated findings on AP repolarization.
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