(A) Experimental trace showing the relaxation of tone in guinea pig trachea (GPT) induced by treatment with indomethacin (INDO), ONO-8130 (O8130) or monoclonal PGE2 antibody (2B5) added at the arrow. (B) Time course of change in spontaneous tone in GPT after addition of the selective DP1 receptor antagonist BWA868c (BWA), EP1 receptor antagonist ONO-8130 (O8130), EP2 receptor antagonist PF-04418948 (PF), FP receptor antagonist AL-8810 (AL), IP receptor antagonist CAY10441 (CAY), TP receptor antagonist SQ-29548 (SQ) or COX inhibitor INDO. (C) Relaxation of spontaneous tone in GPT subsequent to addition of monoclonal PGE2 antibody (2B5) in the absence of indomethacin. (D) Removal of spontaneous tone in guinea pig tracheal segments with or without tracheal epithelium, treated with 3 μM indomethacin. (E) Relaxation of spontaneous tone in guinea pig trachea subsequent to addition of FR-122047 (FR; 1 μM), SC-560 (SC; 1 μM), etoricoxib (ETO; 1 μM) or lumiracoxib (LUMI; 1 μM). Data represent mean ± SEM (n = 4–6).