KCNJ5 and atrial fibrillation: Regarding adenosine-induced atrial fibrillation, a study with 37 human hearts showed that GIRK4 channel blockade might prevent the shortening of action potential and subsequent atrial fibrillation, as these channels, along with adenosine 1 receptor, were overexpressed in those areas with greatest adenosine-induced action potential shortening [98].