Fig. 6.

Analysis of cardiac transient outward K⁺ currents (I_to), sustained K⁺ currents (I_Ksus), and inward rectifier K⁺ currents (I_K1) from isolated atrial cardiomyocytes in nontransgenic (NTG) and FK506-binding protein 12 transgenic (αMyHC-FKBP12) mice. A: representative I_to traces of NTG and αMyHC-FKBP12 myocytes. I_to was elicited from a holding potential at −50 mV with a 50-ms ramp from −80 to −40 mV followed by depolarizing pulses from −40 to +50 mV for 625 ms (in 10-mV increments). B and C: current-voltage (I-V) relationship (I-V curve) for I_to and I_Ksus. NTG: n = 21 cells/4 mice and αMyHC-FKBP12: n = 14 cells/4 mice. D: representative I_K1 traces of NTG and αMyHC-FKBP12 myocytes. I_K1 was elicited by holding the cell at −40 mV followed by 10-mV steps from −120 to 50 mV for 300 ms. E: I-V curve for I_K1. NTG: n = 22 cells/4 mice and αMyHC-FKBP12: n = 18 cells/4 mice. WT, wild type.