Figure 7. Overexpression of CaMKII increases heart rate, reduces arrhythmogenesis and improves Ca²⁺ dynamics.

A: Typical records of control flies and heterozygous flies that contain one extra copy of CaMKII (CaMKII-OE). Flies that overexpress the kinase exhibited increased spontaneous frequency and fluorescence amplitude compared with control flies. B: Summary data showed changes in transient Ca²⁺ dynamics, like the rise of fluorescence amplitude (top, left graph) and the maximal rate of rise of fluorescence +dF/dt_max without changes in −dF/dt_max (top, right graph). FDHM was not changed with CaMKII overexpression (bottom, left graph) and TTP was shortened (bottom, middle graph) without changes of t_1/2 (bottom, right graph). An increment of spontaneous frequency (C) and reduction of arrhythmicity index (D) was observed in CaMKII-OE flies. Mean ± SEM of 28 flies. *p≤0.05.