a | Fig. 1*C*, upper panel | Nonnormal distribution | Wilcoxon matched pairs test | |

| WT vs. pH | | | *z =* 1.68, *n* = 6; *p =* 0.090 |

| WT vs. ΔN | | | *z =* 2.09, *n* = 6; *p =* 0.031 |

| pH vs. ΔN-pH | | | *z =* 2.09, *n* = 6*; p =* 0.031 |

| ΔN vs. ΔN-pH | | | *z =* –0.84, *n* = 6; *p =* 0.840 |

b | Fig. 1*C*, lower panel | Nonnormal distribution | Wilcoxon matched pairs test | |

| WT vs. pH | | | *z =* 0, *n* = 6; *p =* 1.000 |

| WT vs. ΔC | | | *z =* –1.04, *n* = 6; *p =* 0.312 |

| pH vs. ΔC-pH | | | *z =* 0, *n* = 6; *p =* 1.000 |

| ΔC vs. ΔC-pH | | | *z =* 1.46, *n* = 6; *p =* 0.160 |

c | Fig. 1*D*, upper panel | Nonnormal distribution | Wilcoxon matched pairs test | |

| WT vs. pH | | | *z =* –0.21, *n* = 6; *p =* 0.840 |

| WT vs. ΔN | | | *z =* 0, *n* = 6; *p =* 1.000 |

| pH vs. ΔN-pH | | | *z =* 1.25, *n* = 6; *p =* 0.109 |

| ΔN vs. ΔN-pH | | | *z =* 1.35, *n* = 6; *p =* 0.093 |

d | Fig. 1*D*, lower panel | Nonnormal distribution | Wilcoxon matched pairs test | |

| WT vs. pH | | | *z =* –0.63, *n* = 6; *p =* 0.563 |

| WT vs. ΔC | | | *z =* –1.26, *n* = 6; *p =* 0.219 |

| pH vs. ΔC-pH | | | *z =* –1.26, *n* = 6; *p =* 0.922 |

| ΔC vs. ΔC-pH | | | *z =* –1.05, *n* = 6; *p =* 0.891 |

e | Fig.1 F | Nonnormal distribution | Mann-Whitney *U*-test | |

| WT vs. ΔNTD | | | *U =* 68, *n* = 12,12; *p =* 0.843 |

| WT vs. ΔCTD | | | *U =* 93, *n* = 12,12; *p =* 0.242 |

f | Fig. 1*G*, upper panel | Nonnormal distribution | Mann–Whitney *U* test | |

| WT vs. ΔNTD | | | *U =* 12, *n* = 12,12; *p =* 5.8 × 10^{–4} |

| WT vs. ΔCTD | | | *U =* 36, *n* = 12,12; *p =* 0.040 |

g | Fig. 1*G*, lower panel | Nonnormal distribution | Mann–Whitney *U* test | |

| WT vs. ΔNTD | | | *U =* 72, *n* = 12,12; *p =* 0.976 |

| WT vs. ΔCTD | | | *U =* 62, *n* = 12,12; *p =* 0.562 |

h | Fig. 2*B* | Normal distribution | One-way ANOVA | *F*(2,28) = 118.15, *p =* 2.24 × 10^{–14} |

| Mock vs. WT | | *Post hoc* Tukey | *p =* 1.70 × 10^{–13} |

| Mock vs. KCC2-pH_{ext} | | *Post hoc* Tukey | *p =* 3.75 × 10^{–13} |

| WT vs. KCC2-pH_{ext} | | *Post hoc* Tukey | *p =* 0.89 |

i | Fig. 2*C* | Normal distribution | One-way ANOVA | *F*(2,29) = 12.46, *p =* 1.24 × 10^{–4} |

| Mock vs. WT | | *Post hoc* Tukey | *p =* 2.36 × 10^{–4} |

| Mock vs. KCC2-pH_{ext} | | *Post hoc* Tukey | *p =* 8.85 × 10^{–4} |

| WT vs. KCC2-pH_{ext} | | *Post hoc* Tukey | *p =* 0.95 |