Figure 1.

Synergistic effects of TRPA1 and TRPV1 agonists on vagal pulmonary C-fibers. A: experimental records illustrating responses of a pulmonary C-fiber arising from the lower lobe of right lung to intravenous bolus injections of allyl isothiocyanate (AITC; 0.75 mg/kg), capsaicin (Cap; 0.75 μg/kg), and a combination of AITC and Cap at the same doses in an anesthetized and artificially ventilated rat (body weight: 310 g). The same volume (0.15 ml) was delivered in all three injections, first into the catheter (dead space volume 0.2 ml) and then flushed (at arrow) into the right atrium by a bolus of 0.3 ml saline. The interval between injections was 20 min. AP, action potential; P_tr, tracheal pressure; ABP, arterial blood pressure. B: histograms of pulmonary C-fibers activity (FA) to intravenous injections (dashed line) of AITC (0.50–0.75 mg/kg), Cap (0.35–0.75 μg/kg), and a combination of AITC and Cap at the same doses. Data are means ± SEM. Imp/s, impulses per second. C: responses of a pulmonary C-fiber arising from the lower lobe of right lung to intravenous bolus injections of cinnamaldehyde (CinA, 1.8 mg/kg), Cap (0.5 μg/kg), and a combination of CinA and Cap at the same doses (body weight: 280 g). Descriptions in D are similar to that of B, except that AITC was replaced by CinA (1.5–2.0 mg/kg). (Modified from reference 28)