CACNA1D and atrial fibrillation: Zhang et al. (2005) showed that intracardiac atrial stimulation induced atrial fibrillation and atrial flutter in Cav1.3−/− mice but not in wild-type littermates even in the absence of vagal stimulation with carbachol, a muscarinic agonist which is known to induce atrial fibrillation in control mice (Kovoor et al., 2001).