Enhanced Ca2+ sensitivity in hyperresponsive cultured bronchi is mediated by TNFα and NF-κB

The mechanical properties and Ca2+ sensitivity of an or gan-culture model derived from guinea pig airways have been examined. The Cultured explants develop airway hyperresponsiveness to pharmacological agonists after 3-day Culture, when compared with fresh and ovalbumin-sensitized tissues. The reactivity of cultured explants is dependent on the presence of the epithelium. They are also sensitive to glucocorticosteroid pretreatments, which neutralize the TNF alpha antibody and NF-kappa B inhibitor. Hence, specific immunostaining of NF-kappa B Subunits (p65 and p50) was increased in the nuclear extract Of Cultured explants. In beta-escin-permeabilized preparations, step-increases in pCa revealed enhanced Ca2+, sensitivity of the contractile apparatus in Cultured explants, which was prevented by epithelium removal. Pretreatments of cultured explants with neutralizing TNF alpha antibody and NF-kappa B inhibitor consistently reduced their Ca2+ sensitivity. These findings suggest that AHR developed in this organ Culture model may be triggered by an inflammatory process mediated by the TNF alpha and NF-kappa B transcription factor, which results in an increased sensitivity to [Ca2+],.