Figure 2

Limiting Ca²⁺ transients in the heart with nifedipine and aequorin reconstitution protocol. (A) Representative luminescence of a beating heart in a 3 dpf Tg(myl7:GA) larva incubated with 50 µM diacetyl h-CTZ in E3 medium for 2 h. Images were acquired at 9 Hz. The image represents the integrated luminescence of the entire experiment, including Triton X-100. Regions of interest (ROI) from heart and background are shown. (B) Scheme of the aequorin reconstitution protocol comprising a 30-min incubation with nifedipine in E3_0Ca medium to block Ca²⁺ transients, 2 h for aequorin reconstitution with CTZ, and 30 min for recovery of the Ca²⁺ transients in Ca²⁺-containing E3 medium. (C) Representative Ca²⁺ transients of a 3 dpf Tg(myl7:GCaMP)^s878 larva in basal conditions incubated with 25 μM nifedipine for 30 min in E3_0Ca medium, and after the heart recovery period. The fluorescence images were acquired at 200 Hz in a spinning disk confocal microscope; GCaMP fluorescence was measured in a ROI drawn over the ventricle.