FIGURE 1.

Proton-gated currents in SGNs. (A) Current–pH curves. ASIC activation (blue squares) was fitted with a sigmoidal equation, resulting in a pH₅₀ of 6.17 ± 0.05 and a slope of 0.43 ± 0.05; r² = 0.99. The data represent the means ± SEM of at least six neurons. The top recordings show the activation of the proton-gated current by the different pH values indicated above each trace. The grey bar shows the pH change (5 s), and the dotted line indicates zero current. ASIC steady state desensitization (red circles) was fitted with a sigmoidal equation, resulting in a pH₅₀ of 7.3 ± 0.03 and a slope of 0.14 ± 0.03; r² = 0.99. The points represent the means ± SEM of at least four neurons. The bottom recordings show the currents activated by the pH 6.1 solution after perfusion in the conditional pH. (B) Na⁺-free solution reversibly abolished the proton-gated current. (C) Amiloride (100 μM), a non-specific ASIC blocker, reversibly blocked the proton-gated current.