| Influence of the epithelium on the contraction of guinea pig isolated tracheal smooth muscle. |
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O Jung Kwon1, Sang Heon Cho1, In Won Park1, Young Whan Kim1, Sung Koo Han1, Young Soo Shim1, Keun Youl Kim1, Yong Chul Han1, S.H. Seoh2, K.W. Kim2 |
1Department of Internal Medicine, College of Medicine Seoul National University,
2Department of Physiology, College of Medicine Seoul National University, Seoul, Korea |
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| Abstract |
It has been well known that the integrity of airway epithelium is important in development of bronchial hyperreactivity and bronchial asthma. But the mechanisms involved are still unclear.
To evaluate that airway epithelium is able to modulate the contraction of guinea pig tracheal smooth muscle, we investigated the responsiveness of intact and epithelium-denuded tracheal strips to histamine and acetylcholine. And to evaluate whether cyclooxygenase products play a role in this modulatory mechanism, we also investigated the effect of indomethacin pretreatment on the tracheal responsiveness to histamine.
Results
were as follows:
1) In guinea pig tracheal smooth muscle the presence of airway epithelium significantly reduced the response to histamine.
2) In the presence of indomethacin dose-response curves and EC50 values were similar between intact and epithelium-denuded tracheal strips, that is, indomethacin abolished the influence of epithelium on the contracion of tracheal smooth muscle.
3) The response of tracheal smooth muscle to acetylcholine was similar both in the presence and absence of epithelium.
These results suggest that airway epithelium of guinea pig may generate an inhibitory signal to decrease the response of tracheal smooth muscle to histamine and cyclooxygenase products may contribute to the modulation of airway epithelium on the contraction of tracheal smooth muscle. |
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