Differential subunit composition of the G protein–activated inward-rectifier potassium channel during cardiac development
J. Clin. Invest. Bernd K. Fleischmann, et al. 114:994 doi:10.1172/JCI15925 [Go to this article.]

Figure 7
Rectification of I_K,ACh decreases during cardiac development. (A) Steady-state I-V relation of I_K,ACh (voltage steps from _80 mV to 40 mV in 20-mV steps) determined in early- (open squares) and late-stage (filled squares) atria-derived cardiomyocytes. Rel. current, relative current. (B) Original I_K,Ach-mediated currents induced by CCh and recorded at potentials of _80, _40, 0 mV (gray traces) and 40 mV (black trace) in early- and late-stage atria-derived cardiomyocytes; short lines indicate zero current. Note the difference in outward current amplitude. (C) Steady-state I-V relation determined in oocytes injected with Kir3.1 and Kir3.4 cRNA at the ratios indicated. (D) I_K,Ach-mediated current recorded in a late-stage ES cell_derived cardiomyocyte (recorded with perforated patch) in response to a 500 ms voltage ramp from _100 to 60 mV under symmetrical K⁺ conditions with 100 μM Cs⁺ present in the bath medium. Note complete block of channels by Cs⁺ at _100 mV.