FIGURE 8.

Double mutations of αHis⁴⁶⁸ and βHis¹⁶⁰ or γHis²⁷⁷ eliminate the inhibitory effect of 10 μm Cu²⁺ on hENaCs. Oocytes expressing two mutant hENaC subunits and one WT hENaC subunit were clamped to −100 mV. The effects of 10 μm Cu²⁺ were examined together with WT αβγ hENaCs in the same way as in previous figures. A–C, representative recordings showing the responses of the double mutants to 10 μm Cu²⁺. Gray bars show the presence of 10 μm amiloride. D, I_Cu/I obtained from four or five oocytes expressing the double mutants. Black bars show that the values were significantly different from that of WT obtained in the same batches of oocytes (p < 0.001). The dashed line shows the average I_Cu/I from all WT expressing oocytes used in this particular experiment (0.16 ± 0.01, n = 19) for the purpose of reference. Bath solution was buffered with 10 mm HEPES.