Concentration-dependent potentiation of proton-gated currents by prokineticin 2. (A) Sequential current traces illustrate the potentiation of proton-induced currents by different concentration of PK2 on a DRG neuron. Proton-gated currents were elicited by application of pH 5.5 for 5 s durations. The pretreatment time for PK2 was 60 s. (B) PK2 concentration-dependently potentiated proton-gated currents (IpH5.5). Each point represents the mean ± SEM of 6 to 10 neurons. DRG: dorsal ganglia root; PK2: prokineticin 2.