There is one type of potassium voltage-gated channels open in Phase 1 too. Some call them early repolarization channels.
I am not convinced that the channels are different in different phases: 0, 2, 3 and 4.
I think all these potassium channels are voltage-gated. However, they probably differ in some places. I am not sure if one type of channel can be open in all these five phases.
Which types of potassium channels are open during the action potential of cardiomyocyte?