Figure 2.

Time course of the whole-cell conductance measured in oocytes coexpressing CFTR and α-, β-, and γ-ENaC (A) or MDR1 and α-, β-, and γ-ENaC (B). Amiloride (Amil; 10 μmol/liter) blocked most of the whole-cell conductance when applied under control conditions. In CFTR-expressing oocytes, the effect of amiloride was attenuated after stimulation with IBMX and forskolin. After washout of IBMX/forskolin (30 min), the initial effect of amiloride was recovered. In MDR1-expressing oocytes the effects of amiloride were independent of cAMP-dependent stimulation.