A, exemplar recordings showing effect of CFP‐tagged RGK proteins on field stimulation‐evoked rhod‐2‐reported Ca2+ transients in adult rat cardiomyocytes. B, relative impact of distinct RGK proteins on Ca2+ transient amplitude for uninfected (light grey, n = 12), CFP‐Rad (black, n = 19), CFP‐RadS105N (checkered black, n = 15), CFP‐Rem (red, n = 21), CFP‐RemT94N (checkered red, n = 17). C, fraction of cells unresponsive to field‐stimulation for distinct RGKs. D, dependence of relative Ca2+ transient amplitude on expression levels of CFP‐Rad (black circles, n = 19) and CFP‐RadS105N (red circles, n = 15). E, dependence of relative Ca2+ transient amplitude on expression levels of CFP‐Rem (black triangles, n = 21) and CFP‐RemT94N (red triangles, n = 17). P < 0.05, one‐way ANOVA with Bonferroni post hoc analyses.