Figure 5

Inwardly rectifying K⁺ currents, I _K1 , in ED11 atrial and ventricular myocytes. Panel A and B are representative I_K1 current recordings from ED11 atrial and ventricular myocytes. The currents were evoked by depolarizing voltage steps between -120 and 0 mV with an interval of +10 mV from a holding potential of -40 mV in normal Tyrode solution. C: I-V relationships of I_K1 in ED11 atrial and ventricular myocytes in the presence (black triangle and square) and absence (open triangle and square) of 100 μM Ba²⁺. The data are presented as Mean ± SE and are the average from 9 ED11 atrial myocytes, and 10 ventricular myocytes. D: Comparison of I_K1 current densities of ED11 atrial and ventricular myocytes at -120 mV. The I_K1 current densities were calculated as 100 μM Ba²⁺ sensitive K⁺ currents. At -120 mV, the I_K1 current density in ED11 atrial myocytes is about 5 times less than in ventricular myocytes.