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. Author manuscript; available in PMC: 2019 Dec 3.
Published in final edited form as: Pflugers Arch. 2017 Dec 27;470(4):599–611. doi: 10.1007/s00424-017-2099-3

Figure 1. Kir2.1, HCN2, or HCN4 channels maintain resting membrane potential comparable to their reversal potentials in 5 and 2 mM [K+]e when heterologously expressed in CHO cells.

Figure 1.

(A-C) Resting membrane potentials (RMP, top) and whole-cell ramp currents (middle) of CHO cells that express human (A) Kir2.1, (B) HCN2, or (C) HCN4 channels are shown before and after Na+-based bath solutions were changed from 5 (bold black lines) to 2 (bold pink lines) mM K+. Top row: Membrane potentials monitored continuously during changes in [K+]e; time scale, 100 s. Middle row: Whole-cell ramp currents recorded in 5 (black lines) and 2 mM (pink lines) [K+]e; HCN2 and HCN4 channels had reversal potentials of −26.4 ± 1.4 mV (n=5) and −21.5 ± 0.7 mV (n=9) in 5 mM [K+]e, respectively, and −29.5 ± 1.5 mV (n=5) and −25.6 ± 0.4 mV (n=9) in 2 mM [K+]e, respectively. Bottom row: Resting membrane potentials (filled bars) of CHO cells that express Kir2.1 or HCN2 or HCN4 channels and reversal potentials (open bars) of these channels in 5 mM and 2 mM [K+]e (n=5–9).