Apparently in cardiomyocytes, there is an inward rectifying potassium channel that operates during phase 4 of the cardiomyocyte action potential. I have heard that despite this potassium channel being referred to as an inward rectifying channel, that in vitro the channel in fact still transports potassium from the inside to the outside of the cell. It appears that wikipedia seems to suggest otherwise (?).
Can someone please explain what the inward rectifier potassium channel does and its role in phase 4 of the myocyte action potential?