Figure 2. Functional expression of I_f in ES cell-derived cardiomyocytes at different stages of development.

A, the percentage of cells expressing I_f declined during cardiomyogenesis. B, at later stages of development an increase in the current density (I_f/C_m, where C_m is membrane capacitance) of I_f was observed. I_f was evoked by applying a 2 s hyperpolarizing voltage step from a holding potential of −35 to −110 mV (*statistically significantly different to EDS and IDS at the P < 0.05 level using Student's unpaired t test). Numbers above bars are numbers of replicates.