Fig. 3

Basal cardiac Ca²⁺ kinetics of 3 and 5 dpf zebrafish larvae. (A) Emission ratio images of atrial and ventricular systoles of 3 and 5 dpf Tg(myl7:Twitch-4) representative larvae. (B) Atrial and ventricular Ca²⁺ levels (emission ratio) over time calculated from larvae in A. (C) Ventricular Ca²⁺ levels (L/Lmax) of 3 (n = 22, N = 8) and 5 dpf (n = 13, N = 5) Tg(myl7:GFP-Aequorin) larvae measured with a luminescence method. (D) Lissajous diagrams of the ventricular vs. atrial Ca²⁺ in several cardiac cycles from the 3 dpf larva traces in B. The arrows indicate the phases of the cardiac cycle. (E) Diagrams of the ventricular vs. atrial Ca²⁺ levels of the 3 and 5 dpf larvae in B (one cardiac cycle). The distance between arrowheads in these loops represents 20 ms, showing the direction of time and the relative speed of each phase. (F) Kinetic parameters extracted from atrial and ventricular Ca²⁺ traces of 3 (n = 100, N = 12) and 5 dpf (n =68, N = 7) Tg(myl7:Twitch-4) larvae (see Methods for parameter definition). Statistical analysis was performed as indicated in Supplementary data 1. Data are shown as mean ± SD (*** p < 0.001, **** p < 0.0001).