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Fig. 1. Whole-cell currents (command voltages applied for 500 ms between −140 and +40 mV in 20 mV increments) in an oocyte expressing wild-type hENaC a in the absence of PMA and amiloride, b in the absence of PMA but in the presence of amiloride, c in the presence of PMA but in the absence of amiloride, and d in the presence of both PMA and amiloride. PMA markedly decreased oocyte amiloride sensitivity, consistent with inhibition of hENaC
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Fig. 2. Whole-cell currents (command voltages applied for 500 ms between −140 and +40 mV in 20 mV increments) in an oocyte expressing wild-type hENaC a in the absence of PDD and amiloride, b in the absence of PDD but in the presence of amiloride, c in the presence of PDD but in the absence of amiloride, and d in the presence of both PDD and amiloride. PDD had no effect on oocyte amiloride sensitivity
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Fig. 3. Whole-cell currents (command voltages applied for 500 ms between −140 and +40 mV in 20 mV increments) in an oocyte expressing wild-type hENaC a in the absence of PMA + calphostin C and amiloride, b in the absence of PMA + calphostin C but in the presence of amiloride, c in the presence of PMA + calphostin C but in the absence of amiloride, and d in the presence of both PMA + calphostin C and amiloride. Calphostin C significantly reduced the decrease in oocyte amiloride sensitivity produced by PMA alone (see Fig. 1 for comparison)
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Fig. 4. Whole-cell currents (command voltages applied for 500 ms between −140 and +40 mV in 20 mV increments) in oocytes expressing a–d β-subunit Liddle-mutated hENaC, e–h γ-subunit Liddle-mutated hENaC, or i–l both β- and γ subunit Liddle-mutated hENaC, a, e, i in the absence of PMA and amiloride, b, f, j in the absence of PMA but in the presence of amiloride, c, g, k in the presence of PMA but in the absence of amiloride, and (d, h, l) in the presence of both PMA and amiloride
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Fig. 5. Summary of amiloride-sensitive whole-cell Na+ currents (recorded at −100 mV) in oocytes a expressing wild-type hENaC in time controls (open bars, n = 12), and 30 min after the addition of PMA (diagonally hatched bars, n = 23), PDD (solid bars, n = 6), or PMA+ calphostin C (horizontally hatched bars, n = 8), and b expressing Liddle-mutated β-subunit (diagonally hatched bars, n = 14), Liddle-mutated γ-subunit (solid bars, n = 16), or both Liddle-mutated β-and γ-subunits (horizontally hatched bars, n = 9), 30 min after the addition of PMA, with accompanying time controls (open bars, n = 4)
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