FIGURE 4.

Dynamics of Ca²⁺-CaM signals from FRET-based biosensors in adult cardiomyocytes. A and B, normalized tracings of fluorescence signals of BsCaM-2, BsCaM-45, and Ca²⁺ transients from cells paced at 0.1 Hz (A) and 1.0 Hz (B). Inset, tracings with representative beats indicated. C, averaged data of time to peak of the F₄₈₀/F₅₃₀. n = 6–10. *, p < 0.05 versus Ca²⁺ transient at the same frequency. D, averaged data of time constant (τ) of the decay of the F₄₈₀/F₅₃₀. The data of BsCaM-45 and Ca²⁺ transient was zoomed in and showed as inset. n = 6–10. *, p < 0.05 versus Ca²⁺ transient at the same frequency; #, p < 0.05 versus 0.1 Hz in the same group.