Fig. 1

Ionic currents in hESC-RPE and their variability. A Bright-field microscopy image of hESC-RPE monolayer with the patch pipette attached to the cell. Scale bar is 10 μm. B Experimental protocol to record I_Na; a 50-ms pulse to −80 mV was given from a holding potential of −70 mV to measure leak current and membrane capacitance; a 50-ms pre-pulse to −170 mV was used to recover I_Na before stimulating with 50-ms testing pulses in 10 mV increments from −80 to 100 mV. C, D Examples of whole-cell currents recorded from two cells; I_C, residual capacitive current; I_Na, voltage-activated Na⁺ current; I_A and I_DR, the transient and sustained outward voltage-activated K⁺ currents, respectively. E An example of sustained hyperpolarization-activated inward current (I_IR)