The cardiac action potential plateau
What produces the plateau phase of a ventricular muscle cell's action potential?
Answer A: explanation for every choice
A
Correct. The plateau prolongs the action potential and refractory period, which prevents tetanic contraction of the heart.
B
Fast Na+ entry causes the rapid upstroke (phase 0).
C
Cl− currents are not responsible for the plateau.
D
The pump restores gradients slowly and doesn't produce the plateau.
TakeawayVentricular plateau: L-type Ca2+ in, K+ out.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb175.