In addition to effects on the three proteins shown in this scheme, there may perhaps be additional effects mediated by AC8 and AC1 on potassium channels, for example to enhance the amplitude and kinetics of IKs which is also targeted by PKA (Marx et al., 2002), and the consequent more rapid repolarization might be especially important in atrial fibrillation. Here, ADCY8 is linked to atrial fibrillation.