How Hyperpolarization and the Recovery of Excitability Affect Propagation through a Virtual Anode in the Heart

Figure 3

Voltage 𝑉 as a function of position 𝑥, at four times. (a) For an S2 of 13 times threshold at 𝑡₂=285 ms, the stimulus does not excite an action potential. (b) For an S2 of 14 times threshold at 𝑡₂=285 ms, an S2 action potential propagates along the strand until about 𝑥=10 mm, after which it dies. (c) For an S2 of 13 times threshold at 𝑡₂=290 ms, an S2 action potential propagates along the entire strand. (d) For an S2 of 14 times threshold at 𝑡₂=290 ms, an S2 action potential propagates along the strand until 𝑥=10 mm and then dies.

(a)

(b)

(c)

(d)