FIGURE 3.

Protons evoke calcium influx through hTRPA1 but not through rodent TRPA1. A, upper panel, representative snapshots of hTRPA1-expressing cells loaded with FURA-2 during application of control solution (basal), pH 5.0, and 300 μm carvacrol. Lower panel, average effects of pH 6.4 (n = 148), 6.0 (n = 140), and 5.0 (n = 150) as well as 300 μm carvacrol on intracellular calcium in cells expressing hTRPA1 as determined by ratiometric imaging. Protons and carvacrol were both applied for 30 s. B and C, average effects of pH 5.0 on non-transfected HEK-293t cells (B) and on cells expressing mTRPA1 (C) or rTRPA1 (C) as determined by ratiometric imaging. Note that the minimal effect caused by application of protons and carvacrol in HEK-293t cells is due to an application artifact. D, areas under the curve for the average responses evoked by protons in hTRPA1, mTRPA1, rTRPA1, and non-transfected HEK-293t cells. All data are displayed as mean ± S.E. n.s., not significant.