Fig. 2

Atrial and ventricular Ca²⁺ handling in sibling, Tg-plnb^wt and Tg-plnb^R9C 3 dpf zebrafish larvae expressing mCyRFP1-GCaMP6f (A-F) or GFP-Aequorin (G). A) Ratiometric images from beating hearts and their corresponding atrial and ventricular Ca²⁺ traces (ratio) from representative sibling, Tg-plnb^wt and Tg-plnb^R9C larvae. B) Diagram of the ventricular vs. atrial Ca²⁺ levels from the larvae in A. The arrow indicates the direction of time; ?18 cardiac cycles are shown. C) Atrial and ventricular Ca²⁺ transient amplitude (CaT), D) atrial and ventricular Ca²⁺ rise slopes, E) atrial and ventricular Ca²⁺ decay slopes, F) frequency of the CaT (HR) from sibling (n = 34), Tg-plnb^wt (n = 31) and Tg-plnb^R9C (n = 34) zebrafish larvae. G) Time-averaged ventricular Ca²⁺ levels (L/Lmax) from sibling (n = 6), Tg-plnb^wt (n = 7) and Tg-plnb^R9C (n = 11) zebrafish larvae expressing GFP-Aequorin reconstituted with diacetyl h-coelenterazine; images were acquired at 1 frame/s. Statistical analysis was performed using a one-way ANOVA test with Tukey's multiple comparisons post-test. Data are shown as mean ± SD (* p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001). The microscopy chamber temperature was 28 °C.