Figure 7.

Formaldehyde enhances carbachol-induced airway narrowing in PCLSs. PCLSs were exposed to PBS or formaldehyde (0.2, 0.8, or 2 ppm) for 1 hour and then incubated for 24 hours before determining the carbachol-induced contractile response. (A) Slices exposed to 2 ppm carbachol (inverted open triangles) showed a left shift in the carbachol dose–response curve, indicating enhanced sensitivity (mean ± SEM; n = 5–6 donors). (B) There was little effect on the maximal response to carbachol after formaldehyde exposure (mean ± SEM; n = 5–6 donors). (C) The half-maximal effective concentration (log EC₅₀) of the carbachol dose–response curve was significantly decreased in slices exposed to 2 ppm formaldehyde compared with that of PBS-treated slices (mean denoted by black horizontal lines; n = 5–6 donors; *P = 0.019). (D) The AUC of carbachol dose–response curve was significantly elevated in slices exposed to 2 ppm formaldehyde compared with that of slices exposed to PBS (mean ± SEM; n = 5–6 donors; *P = 0.049).