Fig. 9.

IP₃-mediated perinuclear Ca²⁺ release in a permeabilized juvenile cardiomyocyte. Representative cellular Ca²⁺ transients (ΔF/F₀) and fluorescence images (a–c) evoked by extracellular application of 20 μM IP₃ before (left) and after (right) 5-min incubation in 40 μM ryanodine. The normalized fluorescence images were recorded at 240 frames/s before activation (a) and at the peak of the IP₃-activated responses, which normally invaded the entire cell (b) but were confined to the nuclear region after ryanodine treatment (c).