Figure 6.

Responses of TRPA1 to weak acids self-desensitize and cross-desensitize responses to Cin. Whole cell currents evoked in HEK-293 cells expressing TRPA1. (A) TRPA1 currents evoked in response to 10 mM of acetic acid, pH 5, decayed after activation and could not be evoked again by acetic acid, indicating that the channels had entered an inactivated state. (B) After inactivation by 10 mM of acetic acid, pH 5, TRPA1 currents could not be activated by 100 µM Cin, indicating that acetic acid could cross-desensitize responses to Cin. (C) 100 µM Cin elicited large currents in TRPA1-expressing cells that were not preexposed to acetic acid. Currents were recorded in the absence of extracellular Ca²⁺. Average data are shown below each representative trace. Data are represented by the mean ± SEM. Significance was determined with the two-tailed paired (A; comparison between responses to the first and second application of acetic acid) or unpaired (B and C; comparison between responses to Cin with or without preexposure to acetic acid) Student’s t test. *, P < 0.05; ***, P < 0.001.