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. 2005 Mar 3;564(Pt 3):671–682. doi: 10.1113/jphysiol.2004.079046

Figure 4. Amiloride-induced voltage shift is modulated by membrane conductance changes.

Figure 4

A, when the hCFTR is inactive, rENaC activation by removal of amiloride (indicated by the bar labelled ENaC) depolarizes an oocyte in this example from −16 mV to +13 mV. Activation of the CFTR (by 0.5 mm IBMX + 10 μm forskolin, indicated by the bar labelled CFTR) yields slight hyperpolarization (to −19 mV), and subsequent activation of ENaC depolarizes the oocyte to only −14 mV. The trace shown is representative of seven similar experiments in which voltage-clamp measurements showed that ENaC conductance is not affected by CFTR activation. B, continuous voltage recording from another hCFTR/rENaC-co-expressing oocyte, where CFTR and ENaC were activated in a reversed order compared to A (i.e. CFTR was activated first, at the beginning of the experiment, and then inactivated). The data show increase of ENaC-related, amiloride-induced voltage shift after inactivating CFTR (washout of IBMX/forskolin), demonstrating reversibility of the effect.