FIGURE 1.

Experimental approach to supply a patched atrial myocyte with a synthetic inward rectifier K⁺ current (I_K1). A Real-Time Linux (RT-Linux) based PC computes the synthetic I_K1 according to the membrane potential (V_m) that is read into the PC. After addition of any stimulus current (I_stim), this I_K1 is sent to the patch clamp amplifier, which operates in current clamp mode and injects the net current (I_in) into the patched myocyte. This process is updated with a time step Δt₂ of 40 µs. I_stim is sent out by the Apple Macintosh (Mac) G4 computer that is used to control the experiment and record both V_m and I_in at a rate of 40 kHz, corresponding with a time step Δt₁ of 25 µs. Inset: current–voltage relationship of the synthetic I_K1 with moderate rectification (“Bett” current; Bett et al., 2013) and the synthetic I_K1 with strong rectification (“Kir2.1” current; Meijer van Putten et al., 2015). E_K denotes the potassium equilibrium potential.