Tetrodotoxin and action potentials
Tetrodotoxin blocks voltage-gated Na+ channels. Which effect on a neuron is expected?
Answer D: explanation for every choice
A
The resting potential depends mainly on K+ leak channels.
B
Prolonged action potentials result from blocking K+ channels.
C
Without the Na+ upstroke, there's no action potential to repolarize.
D
Correct. Voltage-gated Na+ channels are closed at rest, so blocking them barely changes the resting potential but prevents depolarization.
TakeawayBlock Na+ channels → no spikes. Block K+ channels → prolonged spikes.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb172.