Fig. 5

JellyOp function in mouse atria of intact hearts. a Section through the right atrium shows GFP (green) and membrane-bound JellyOp-1D4 epitope signals (yellow, nuclear staining in blue, bar: 20 µm, insert: 5 µm). b Analysis of cAMP levels in atrial tissue from JellyOp mice in the dark and after illumination (2.86 μW mm⁻², 5 min) or stimulation with isoprenaline (Iso, 1 µM, 5 min) (n = 4–6, one-way ANOVA: p = 0.0074, Bonferroni post-test: *p < 0.05). c, d Representative heart rate traces of a JellyOp heart during maximal light stimulation of the dorsal right atrium (c, blue bar, 2 mW mm⁻², 90 s) or during perfusion with isoprenaline (d, red bar; 1 µM, 4 min) (gray: original trace, black: running average values). e–g Statistical analysis of the maximal relative heart rate increase (e), activation time (f, stimulation start to 80% of maximum rate), and deactivation time (g, stimulation end to 50% of maximum rate) after illumination (blue, 2 mW mm⁻², 90 s) and perfusion with isoprenaline (red, 1 µM, 4 min) (n = 5, two-sided paired Student's t-test: p = 0.0248 (e), p = 0.0058 (f), p = 0.0017 (g)). h Relative heart rate increase after illumination of the dorsal right atrium with light of wavelengths of 470 nm and 400–700 nm in 50 nm steps (10 µW mm⁻², 1 s, n = 5) fitted with the Govardovskii equation (red line, R² = 0.98). Error bars: S.E.M.