SCN5A and long QT syndrome 3: In the present study, we utilize the Cntn2-EGFP mouse model10, 11 and a well-established murine model of LQT3, the SCN5A ΔKPQ+/− mutant mouse12, 13 (characterized by ventricular arrhythmias and APD prolongation) to isolate and functionally characterize PCs and compare them to VMs.