Figure 1. Cold responses of TRPA1 species variants in Ca²⁺ assay.

(a) In rTRPA1-expressing cells, lowering temperature in steps (from 24 to 20, 18, 16, 14, 12, 10 and 8 °C) evoked progressively larger Ca²⁺ influx, as reflected by increases in relative light unit (RLU). Signals in A967079 (5 μM)-treated rTRPA1 cells and mock-transfected cells were small and overlapped. A967079-specific signals (rTRPA1 subtracted) were obtained to represent TRPA1 activities. (b) Cold increased (Ca²⁺) in cells expressing mTRPA1 but not hTRPA1 or rhTRPA1. Fluorescence traces are shown as mean±s.d. from 12 wells. More than five transfections were performed.