Figure 5.

ET-1 sensitizes TRPA1 channel activated by endogenous agonist H₂O₂ in both HEK293 cells and mouse DRG neurons. (a) Averaged Ca²⁺ responses from HEK293 cells in control condition or treated with ET-1 (100 nM). HEK293 cells were expressed with TRPA1 and ET_AR. H₂O₂ (1 mM) was applied as indicated to induce TRPA1 activation in HEK293 cells. n > 30 cells/group. (b) Summarized amplitude of H₂O₂-induced Ca²⁺ responses in control condition or treated with ET-1. Ca²⁺ responses were normalized to ionomycin (1 µM) applied at the end of the tests (% response of ionomycin). n = 3 tests/group. Each test contains up to 30 cells. (c) Averaged Ca²⁺ responses from mouse DRG neurons in control condition or treated with ET-1 (100 nM). H₂O₂ (1 mM) was applied as indicated to induce TRPA1 activation in DRG neurons. n > 20 cells/group. (d) Summarized Δ increase in ratio of 340/380 of H₂O₂-induced Ca²⁺ responses in DRG neurons as recorded in (c). n = 4 tests/group, each group contains 120–160 neurons from 3 mice. **p < 0.01 versus control group.

HEK293: human embryonic kidney 293 cells; ET-1: endothelin-1; DRG: dorsal root ganglion; Iono: ionomycin.