Fig. 5.

Effects of ouabain and isoproterenol on Ca²⁺ transients during spontaneous contractions of wild-type zebrafish hearts. A: time course of ΔCa²⁺ (calcium green fluorescence intensity) before and after application of 1 μM ouabain or isoproterenol. B: summary data comparing ΔCa²⁺ transients in the absence and presence of ouabain or isoproterenol. ΔCalcium green fluorescence intensity is calculated as the difference of calcium green fluorescence intensity between contraction and relaxation. Data are normalized against control. Values for n are 4 (0.1 μM ouabain), 4 (1 μM ouabain), 4 (0.5 μM isoproterenol), and 4 (1 μM isoproterenol). *P < 0.05.