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Figure 5. Voltage dependence of stationary and ouabain-sensitive transient currents of the ΔYY construct under different ionic conditions and pHext. (A and B) Current recordings at −30 mV from a ΔYY-expressing oocyte in the presence (A) or absence (B) of extracellular Na+ at pH 7.4 and 5.5. If present, [Na+]ext and [NMDG+]ext were 100 mM, and [K+]ext and [ouabain] were 10 mM. The composition of the extracellular solution is indicated above the current traces. Dashed lines indicate the “zero pump current” level (at 10 mM ouabain) as a reference for pump-related currents. (C and D) I-V curves of stationary currents in different extracellular solutions from oocytes expressing ΔYY (C) or ATP1A2 WT (D), each normalized to the NaI10K(ouab) current at 0 mV. Similar data were obtained on at least three different cells. (E) Ouabain-sensitive transient currents of ΔYY at pH 7.4 (NMDGI(ouab) and NaI(ouab)) and pH 5.5 (NMDGI(ouab)5.5 and NaI(ouab)5.5) in the absence of K+ext upon 250-ms voltage steps from −30 to −140 mV. The peak of the NaI(ouab) current is indicated by a dotted line. Note the time axis break (hatched bar). Image published in: Meier S et al. (2010) © 2010 Meier et al. Creative Commons Attribution-NonCommercial-ShareAlike license Larger Image Printer Friendly View

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