Na+ channel dependency

[kkentm]

A question in examkrackers 1001 bio questions gave me an answer stating that the Purkinje fibers of the cardiac conduction pathway are Na+ channel dependent (as opposed to ion channel dependent). I wrote ion channel dependent as my answer because I know action potential propagation relies on the opening of both K+ and Na+ channels. My interpretation of the answer given in the book is that the Purkinje fibers are Na+ channel dependant because it is the first ion gated channel to open in order for depolarization to occur (which is then followed by K+ channels opening leading to hyperpolarization), which is consistent with all neuron cells. Is my interpretation correct or am I missing a piece of information? Thanks

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[PingPongPro]

Its sort of a vague question in my opinion, but I think the EK book is right. Both Na+ and K+ channels open, but everything DEPENDS on Na+ channels opening to start the initial depolarization. Without the initial Na+ channel opening, depolarization will not occur and no action potential will be formed.

Also remember that Ca2+ ion is also a part of cardiac membrane potential.