KCND3 and cardiac arrhythmia: Finally, it should also be noted that Kv4 channels do not only mediate ISA (Kv4.2 in CA1 pyramidals) but also a transient outward current (Ito) in cardiac myocytes (mostly Kv4.3 in humans; [73]) and that, at least in the dog heart, the NS5806-mediated potentiation of Ito has been found to recapitulate certain features of Brugada syndrome, a form of cardiac arrhythmia [39].