TRPA1 agonists allyl isothiocyante and cinnamaldehyde elicit calcium responses with different latencies in DRG neurons.

<p>A. Representative traces of individual, dissociated lumbar 1–6 dorsal root ganglia (DRG) neurons from C57BL/6J wild-type mice during FURA-2 calcium imaging. Separate neurons were tested with 100 µM allyl isothiocyanate (AITC; 1 min; top trace) or cinnamaldehyde (CINN; 3 min; bottom trace) at 6 ml/min. Note that the latency to peak amplitude for CINN responses was longer than that for AITC, whereas responses to 50 mM K+ (30 s) occurred almost immediately after the start of superfusion. B. Average latency from the start of superfusion to maximum amplitude of response for AITC and CINN (3 culture preparations from 5–6 animals for each group). The latency between onset of superfusion and peak response for CINN was significantly longer than that for AITC (p<0.0001; t-test). C–D. Concentration-response curves for AITC (C) and CINN (D) for percentage of responders (left two panels) and peak amplitude of calcium responses (right panel). Neurons that exhibited a ≥20% increase in FURA ratio from baseline during agonist superfusion were considered “responsive” (3 cultures from 5–6 animals for each group; AITC: 446 total neurons; CINN: 281 total neurons). All neurons were tested with only one concentration of one agonist. For percentage of responders, the EC50 for AITC was 38.5 µM and that for CINN was 60.2 µM (both calculated from 10–1000 µM data). For peak response amplitude, the EC50 for AITC was 115.3 µM (calculated from 10–300 µM data) and that for CINN was 97.5 µM (calculated from 10–1000 µM data).