Figure 5
Kinetic model of cardiac Ito current—computed effects of increasing series resistance and current amplitude on current recordings. (A) Expression of the K+ current depending on the activation gate (a), inactivation gate (i), the maximal conductance (Gmax) and the reversal potential for K+ (EK)5. (B) Computed superimposed recordings of the Ito current, for various current amplitudes and series resistances (RS), as indicated. The activation voltage protocol shown (holding potential: − 100 mV; 100-ms pulse at the indicated potentials; one sweep every 2 s) corresponds to the potential experienced by the membrane (Vm), not the potential between the two electrodes (Vcmd). It is thus altered when (Rs x I) is elevated. (C) Activation curves (G/Gmax vs Vcmd) in the three conditions represented in (B). Theoretical half-activation potentials (V0.5) and slopes (k) are indicated in black. V0.5 and k for RS of 0, 5 and 15 MΩ and I peak of 100 nA are indicated in colors.
