FIGURE 8.

The electrophilic compound cinnamaldehyde activates purified AgTRPA1 with and without its N-terminal ARD. A, as shown in experiments measuring ramp currents (−100 to +100 mV in 2 s), AgTRPA1 responded to cinnamaldehyde (100 μm) with macroscopic inward and outward channel currents (black trace) at negative and positive test potentials, respectively. Gray trace, baseline currents. B, at a steady state test potential of −60 mV, distinct single-channel openings were observed for AgTRPA1 with and without its N-terminal ARD (Δ1–766 AgTRPA1). The vehicle (1% ethanol) of cinnamaldehyde did not evoke activation of AgTRPA1 or Δ1–766 AgTRPA1 (see Figs. 6 and 7). Shown are representative traces and corresponding amplitude histograms yielding single-channel conductances of 41 and 57 picosiemens for AgTRPA1 and Δ1–766 AgTRPA1, respectively. Purified AgTRPA1 and Δ1–766 AgTRPA1 were inserted into planar lipid bilayers, and channel currents were recorded with the patch-clamp technique in a symmetrical K⁺ solution (c, closed channel state; downward deflections, open channel state).