A number of studies have previously highlighted a direct link between increased ROS production and the onset of arrhythmias in the ischemic/postischemic heart, either mediated via neutrophils and their release of the defense protein Lcn2 or by alterations in mitochondrial membrane potentials that directly affect the tightly regulated AP (9, 212, 213). Here, LCN2 is linked to cardiac arrhythmia.