Figure 5

Effects of warming on tachyphylaxis of TRPA1. A-B, representative current traces evoked by two consecutive applications of FFA (300 μ M) in two independent HEK293 cells stably expressing human TRPA1. Initially FFA was applied at 23°C for 30 s. During the later half of the first application, FFA was applied at either 23°C (A) or 39°C (B). The second application was performed at 23°C in both groups. The letters a to d indicate time points for the quantification shown in panel C. The arrowhead indicates transient potentiation of TRPA1 currents by heat under this recording condition. Scale bar, 30 s, 4 nA (left), 2 nA (right). C, averaged relative current responses measured at points a to d in panel A and B. Current amplitudes were normalized to the respective peak amplitude during the initial half of the first application of FFA at 23°C. Black and white bars represent groups with or without heat co-application, respectively, during the first FFA application. **P < 0.001 in Student's t test; n = 5.