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. 2008 Oct 16;40(5):543–554. doi: 10.1165/rcmb.2008-0166OC

Figure 6.

Figure 6.

Whole-cell AS Na+ currents in αβγδ human ENaC (hENaC)–expressing oocytes. AS currents were computed as the difference between the currents with and without 10 μM amiloride in the bath. (A) Representative whole-cell current recordings at −100 mV from an oocyte expressing αβγδ hENaC (αβγδ hENaC, top panel) and an uninjected oocyte (control, bottom panel). Oocytes were initially perfused with ND-96 medium. The bath solution was then switched to ND-96 medium plus 10 μM amiloride. This application of amiloride was repeated two additional times to the same oocyte, as indicted by solid bars. The dashed lines indicated zero current level. (B) Analysis of Na+ currents (I) in uninjected (control) and αβγδ hENaC–expressing oocytes (αβγδ hENaC). ND-96, amiloride, and AS represent Na+ currents recorded in ND-96 medium, ND-96 medium plus 10 μM amiloride, and subtraction of these two (AS currents), respectively. This result is consistent with (A) (bottom), showing that there are no AS Na+ currents in uninjected oocytes. The number in brackets stands for the total oocytes for each group. **P < 0.01, compared between AS of αβγδ hENaC and those of control. (C) Representative whole-cell Na+ current traces before (ND-96, left) and after application of 10 μM amiloride (amiloride, middle) and their subtraction (AS, right) from an uninjected oocyte (control, top) and an oocyte expressing αβγδ hENaC (αβγδ hENaC, bottom). Oocytes were held at −40 mV, and then stepped from −120 mV to +80 mV in 20-mV increments. (D) Current–voltage relationships. Whole-cell Na+ currents (I) at membrane potential (Vm) from −120 mV to +80 mV were recorded from an uninjected oocyte (control, top) and oocytes expressing αβγδ hENaC (αβγδ hENaC, bottom). Average current levels of total (ND-96, triangle), amiloride-resistant (Amiloride, circle), and AS Na+ currents (AS, square) were plotted as a function of Vm. (E) Resting Vms in oocytes expressing αβγδ hENaC (αβγδ hENaC) and uninjected cells (control). The number in brackets stands for the total oocytes for each group. **P < 0.01.