A, Whole cell patch clamp recording of ICa as a function of voltage in WT (left panel) and KO (right panel) cardiomyocytes before and after stimulation by isoproterenol (100 nmol/L) (n=12 cells from 3 animals). B, Whole cell patch clamp recording of ICa as a function of voltage in WT (left panel) and KO (right panel) cardiomyocytes before and after stimulation with forskolin (Fsk, 10 umol/L) (n=10 cells from 3 animals). C, The fold change of the stimulated ICa measured at 10 mV for isoproterenol (Iso, 100 nmol/L) or forskolin (Fsk, 10 umol/L) (mean ± s.e.m., n=3 animals;**P<0.001)