Four groups were assayed: (1) cold anesthesia followed by PBS injection; (2) cold anesthesia followed by 1 X 10-5 M CCAP in PBS; (3) 30 sec FlyNap (FN) anesthesia followed by PBS injection; (4) 30 sec FlyNap anesthesia followed by 1 X 10-5 M CCAP in PBS. The following heart parameters are reported: (A–C) total, anterograde and retrograde contraction rate; (D) frequency of heartbeat directional reversals; (E–F) percent time contracting in the anterograde and retrograde directions; (G–H) anterograde and retrograde period lengths. Data were initially analyzed by repeated measures two-way ANOVA, and for each treatment group the statistical significances between the pre- and post-injection datasets are denoted using asterisks (Sidak’s multiple comparison’s post-hoc test: ns, P>0.05; *, P<0.05; **, P<0.01; ***, P<0.001; ****, P<0.0001). The percentages reported above each set of columns report the percentage change between pre- and post-injection. Bars denote the standard error of the mean. For all groups, N = 10.