Acidic pH increases the activation rate of capsaicin-activated responses of rat TRPV1 channels expressed in HEK-293 cells. Comparison of the activation rate of 1 μM capsaicin-activated currents in rat TRPV1 expressing cells under control conditions (pH 7.4) and after pre-application of acidic solution (pH 5.5). (A) Representative current trace. (B) Overlay of normalized current traces illustrating increased activation rate of capsaicin under acidic conditions. (C) The activation rate of capsaicin-activated currents was significantly faster at pH 5.5 (149 ± 17 ms) than at pH 7.4 (847 ± 119 ms) (n = 4). Data are the mean ± SEM.