A, the C-subunit of PKA (7 μM through pipette, left panel) as well as 8-bromo-cAMP (8-Br-cAMP 200 μM, extracellular application, right panel) stimulated If in EDS cells. The corresponding time courses are shown in B. The effects of C-subunit of PKA (n= 4) and 8-Br-cAMP (n= 5) on If are summarized in the left and right panels of C, respectively. *Statistically significantly different to control (Con) at the P < 0.05 level (paired t test). D shows that 8-Br-cAMP has no additional effect on If after activation of the current by the C-subunit of PKA (7 μM): left panel, current traces (1 control, 2 C-subunit of PKA, 3 C-subunit of PKA + 8-bromo-cAMP); right panel, corresponding time course.