Fig. 5

Fig. 5 Tmem161b is required in the zebrafish heart for correct AP repolarization. (A, Top) Schematic of VSFP-Butterfly biosensor used to report AP dynamics in the live zebrafish heart. (A, Bottom) Heatmap stills from wild-type hearts showing APs initiating in the atrium and progressing through the ventricle. This is absent in grime mutant hearts during arrhythmia episodes. (B) AP graphs showing atrial (A), atrioventricular canal (AV), and ventricular (V) activations over time. Examples of 2 dpf wild-type heart and tmem161b mutant hearts with skipped ventricular beat and 3 dpf with sinoatrial irregularities are shown. Asterisks indicate missing or delayed activations, black arrowheads indicate prolonged repolarization of an AV-canal AP. (C) Average in vivo ventricular AP curves at 2 and 3 dpf for tmem161b+/+ and tmem161b^−/− siblings, demonstrating significantly prolonged repolarization in tmem161b^−/− embryos (mean ± SEM; n = 8 to 12). (D) Graphs of AP repolarization time for the ventricle at 2 and 3 dpf, showing significantly increased repolarization time. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.