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The title says it - I wonder why an increase in extracellular Sodium (Na+) concentration increases action potential amplitude?

What I understand:

I understand that an influx of positively charged Na+ ions into the cell leads to depolarization of the membrane potential (which in a positive feedback loop leads to more ion channels being permeable to Sodium, and hence further depolarization).

I understand that according to the Goldman equation, an increase of extracellular Na+ leads to a less negative resting membrane potential.

What I don't understand:

If the action potential generation happens within a specific time window, and the influx rate of Na+ does not change due to a change of the extracellular concentration, the change in membrane potential during an action potential should be the same (as with a lower level of Na+).

Is the higher action potential amplitude hence due to the less-negative starting point?

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  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – Bryan Krause Jul 18 at 22:38

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