Figure 6.

Block of wt ENaC and mutants by external Zn²⁺. Concentration dependence of Zn²⁺ inhibition of inward Li⁺current. I/I₀represents the current ratio measured in the presence/absence of external Zn²⁺. Inhibitory constants (K _i) were obtained from best fit of the data to a Langmuir inhibition isotherm (dotted lines). Zn²⁺ K _i were >10 mM for wt ENaC (n = 34), 29 μM for αS583C (n = 42), 1.1 mM for βG525C (n = 10), and 1.9 mM for γG537C (n = 14).