Effect of removal of tracheal epithelium on histamine responsiveness and oxygen tension

ABSTRACT

The present study was done to investigate the relation between the hyperresponsiyeness of the isolated guinea pig trachea devoid of epithelium of agonists example histamine and the oxygen tension in the surrounding bathing fluid [Krebs' solution]. Histamine dose response curves were constructed using isolated guinea pig tracheas with intact epithelium and with those devoid of epithelium. The curves of the denuded tracheaI strips showed a parallel shift to the left. Meanwhile the oxygen tension was measured in the bathing surrounding the trachea with intact epithelium and surrounding the trachea with denuded epithelium and compared to the oxygen tension in Krebs solution containing no trachea under constant conditions. It was found that oxygen tension of Krebs' solution surrounding the intact tracheas was highly significantly decreased compared to the solution surrounding the denuded ones which was also decreased but to a lesser extent than the controls. The results of this could suggest that metabolism of oxygen by airway epithelium may contribute towards the modulation of smooth muscle response. Thus, in the absence of the airway epithelium similar to cases of bronchial asthma, there is a decrease in the oxygen metabolism which may be attributed to the hyperactivity of the bronchial muscles leading to bronchoconstriction