Files in this Data Supplement:

• Figure - (JPEG) (24.6 KB) A, Current trace of another S4 triple-pore mutation channel and I-V plot of mean current density. We also made S4 triple (R447N, L448A, and R453I, same as SPC) and pore mutation (V525S, different from SPC). This channel also showed hyperpolarization-activated inward current with steady activation in physiological conditions. Mean current density at -130 mV was -6.1±2.1 pA/pF that was smaller than SPC. Reversal potential was -25±1.9mV (n=5, data not shown). B, ECG lead III in another S4 triple-pore (V525S) virus-treated guinea pig. Black or red arrow indicates junctional rhythm or start of idioventricular rhythms, respectively. Occasionally, junctional escape rhythms could be overtaken by ectopic ventricular pacemaker activity. These ventricular rhythms lasted for 20 seconds.