Figure 1.

Formaldehyde has little effect on agonist-induced intracellular Ca²⁺ [Ca²⁺]_i in human airway smooth muscle (HASM) cells. HASM cells were loaded with the Ca²⁺-binding dye fluo-8 and stimulated with agonists to determine the global changes in [Ca²⁺]_i. There was no significant effect on the (A) bradykinin-induced (1 nM) or (C) histamine-induced (1 μM) [Ca²⁺]_i in cells exposed to formaldehyde. Area under the curves (AUCs) of [Ca²⁺]_i transients induced by (B) bradykinin or (D) histamine were comparable between PBS-treated and formaldehyde-treated HASM cells (n = 3 donors with 3 technical replicates per condition); A and C, mean RFU; B and D, mean ± SEM. FA, formaldehyde; ppm, parts per million; RFU, relative fluorescence unit.