Abstract
Background: Inflammatory conditions can alter responsiveness to the endogenous mediator bradykinin (BK) in mouse and human airway smooth muscle. Guinea-pig and human airways generally display similar smooth muscle responsiveness. The aim of this study was to develop an in vitro-model in guinea pig trachea (GPT) to study the regulation of BK responses by culture procedures.
Methods: The contractile response to BK was determined in organ tissue baths. Either fresh, organ bath incubated (6-12 hours) or in DMEM/ F12 media cultured (4 days) GPT segments were used for these measurements. The contractile responses to BK were determined in the presence of 3μM indomethacin and 10μM captopril. Contractions were presented as a percentage of the maximal contraction of the GPT.
Results: In fresh GPT, BK induced only weak contractions (Emax: 8±2%). This response was not changed after 6 hours incubation, however after 12 hours incubation a strong enhancement of the BK induced contraction was observed (Emax: 53±2%, pEC50 7.4±0.2). This up-regulated response was partly regulated by prostanoids, since both Emax (28±2%) and pEC50 (6.3±0.1) were decreased in segments incubated for 12 hours with indomethacin. In contrast to the 12-hour incubation in the tissue bath, the contractile response to BK after 4 days organ culture was only slightly enhanced (Emax: 21±3%).
Conclusion: This study shows that contractions in GPT to BK are inducible over time. The different effects of incubations in the tissue bath and the organ culture may be used to study different aspects of regulation of BK responsiveness in airway inflammation.
- © 2011 ERS