RPRFa specifically potentiates ASIC3 currents. (A, Top) Representative current traces of homomeric ASIC1a, ASIC1b, and ASIC3, activated with pH 6.5, pH 5.8, and pH 6.3, respectively. Roman numerals mark specific activations. RPRFa (50 μM; red bars) was preapplied at pH 7.4 for 60 s. (A, Bottom) Quantification of ai (n = 10). ***P < 0.001 (Student’s t test). (B) FaNaCs are not affected by RPRFa. Representative current traces illustrating activation of HaFaNaC and AkFaNaC by FMRFa (10 μM; black bars). RPRFa (10 μM; red bars) neither activated FaNaC nor inhibited activation by FMRFa.