Figure 7.

The effects of mammalian TRPA1 agonists and antagonists on Painless. A, B, Painless-expressing cells are not activated by AITC (2 mm; A) or cold stimulation (∼10°C; B) (n = 3–5). Standard bath solution and Cs-Asp/200 nm Ca²⁺ pipette solution were used. Functional Painless expression was confirmed by heat application. C, D, Heat activation of Painless was reversibly blocked by ruthenium red (RuR, 10 μm; C) or camphor (3 mm; D) treatment (n = 6–8). Standard bath solution and Cs-Asp/200 nm Ca²⁺ pipette solution were used. The repeated heating protocol (Fig. 4) was used to validate the function of Painless before and after the treatment with antagonists. Heat termination points are indicated as dotted lines. Cells were treated with each antagonist, followed by application of heated bath solution containing antagonist. The inhibitory effects of ruthenium red were incompletely reversed. Higher concentrations of camphor could not be applied because camphor severely damaged the gigaohm seal.