Acta Pharmacologica Sinica 2006 June; 27 (6): 708-714; doi: 10.1111/j.1745-7254.2006.00334.x

Aim: To find out if the two aspects of asthma (chronic airway inflammation and bronchial hyperresponsiveness) are related to hypersensitivity of calcium signaling in bronchial epithelial cells.

Methods: Porcine bronchial epithelial cells (PBEC) were divided into sensitized (S) and nonsesitized (N) groups. In group S, the cells were preincubated with serum from ovalbumin sensitized guinea pigs. In group N, the cells were preincubated with serum from nonsensitized guinea pigs. Single cell calcium imaging and ELISA-based NF-kB activity were used to evaluate the histamine-stimulated intracellular free calcium level and NF-kB activity, respectively.

Results: First, 0.1 µmol/L histamine could induce [Ca²⁺]_i oscillations in PBEC of group S, but not in group N. Second, 1 µmol/L histamine could induce [Ca²⁺]_i oscillations of PBEC in both group S and group N. The [Ca²⁺]_i oscillation frequency of PBEC was significantly higher in group S than in group N, though the [Ca²⁺]_i oscillation amplitude showed no difference between the two groups. Finally, when 10 µmol/L histamine was used to stimulate PBEC, a transient initial increase followed by a sustained elevation (FSE) of [Ca²⁺]_i was observed in PBEC in both groups. The amplitude of the FSE of [Ca²⁺]_i in PBEC was significantly higher in group S than in group N. The subsequent NF-kB activity was in accordance to the calcium oscillation frequency evoked by histamine, but not to the amplitude.

Conclusion: It was suggested that the increased sensitivity of calcium signaling in bronchial epithelial cells might contribute to the exorbitant inflammation or increased susceptibility in asthmatic airway epithelial cells.

Keywords: asthma; histamine; calcium signaling; bronchi; epithelial cell; nuclear factor of kappaB