Fig. 8

Altered excitation in 3 and 5 dpf zebrafish larvae caused by caffeine. Some Tg(myl7:Twitch-4) larvae treated with 3 mM caffeine showed an altered pattern of atrial and ventricular Ca²⁺ transients. (A) Atrial and ventricular Ca²⁺ levels (emission ratio) before (basal) and after 1 h incubation with 3 mM caffeine in 3 and 5 dpf larvae (representative experiments). The vertical dotted lines show that ventricular Ca²⁺ increased before atrial Ca²⁺ in the 5 dpf larva. (B) Diagrams of the ventricular vs. atrial Ca²⁺ levels (one cardiac cycle) of the larvae in A before (basal) and after 1 h incubation with caffeine. (C) Diagrams of the ventricular diameter vs. ventricular Ca²⁺ level (one cardiac cycle) of the same larvae. The red arrows indicate the start of the atrial systole. Each arrowhead in B and C corresponds to one image: they are separated from each other by 20 ms.