Table 1.

pH-mediated regulation and Na⁺ self-inhibition of δ-ENaC acidic cleft mutants

Individual values for pH-mediated regulation and Na⁺ self-inhibition of Xenopus δβγ-ENaC containing aspartate substitutions in the δ-ENaC acidic cleft derived from recordings as presented in Fig. 7, a–d. Values for maximal activation and minimal activity in the “pH-mediated channel activation” columns are based on individual sigmoidal dose-response functions. Statistical evaluation of these data was performed as follows: maximal activation (Kruskal-Wallis test, p < 0.0001; Dunn's multiple comparisons test); minimal activity (one-way ANOVA, F = 12.11, p < 0.0001; Tukey's multiple comparisons test). Values for V_max and K_m in the “Na⁺ self-inhibition” columns are derived from individual Michaelis-Menten plots where applicable. Statistical evaluation of the corresponding data was performed as follows: V_max (Kruskal-Wallis test, p < 0.0001; Dunn's multiple comparisons test); K_m (Kruskal-Wallis test, p = 0.061; Dunn's multiple comparisons test). All values represent mean ± S.E.

	pH-mediated channel activation			Na+ self-inhibition
	Maximal activation	Minimal activity	n	Vmax	Km (mm Na+)	n
δβγ-ENaC	3.48 ± 0.31a	0.5 ± 0.03a	22	0.72 ± 0.01	3.8 ± 0.7	16
δD105Kβγ	2.04 ± 0.11a,b	0.62 ± 0.02b	14	0.57 ± 0.03b	2.7 ± 1.2	9
δD293Nβγ	1.94 ± 0.07a,b	0.49 ± 0.03a	14	0.62 ± 0.03b	8.9 ± 3.6	16
δD296Nβγ	1.81 ± 0.10b	0.60 ± 0.02a,b	16			12
δD293N,D296Nβγ	1.92 ± 0.09a,b	0.54 ± 0.02a	19			15
δD105K,D296Nβγ	1.7 ± 0.04a,b	0.65 ± 0.02b	17			11
δD105K,D293N,D296Nβγ	1.38 ± 0.04b	0.74 ± 0.03b	12			10

^a p < 0.05 when compared with δ_{D105K,D293N,D296N}βγ-ENaC in the respective column.

^b p < 0.05 when compared with wildtype δβγ-ENaC in the respective column.