A Study on Protease in Tracheobronchial Secretion

3. A Protease-antiprotease System in Tracheobronchial Secretion of Rat

Abstract

In previous papers, we reported that the plasminogen activator existed in the tracheobronchial secretion of normal rats and its activity was modified by some drugs However, the existence of the proactivator, other proteases and antiproteases in the tracheobronchial secretion has not been exactly studied yet In this experiment we examined whether they existed or not in the secretion, and the pH- and thermo-stability of the plasminogen activator was also examined.
The results obtained were as follows.
1. The fibrinolytic activity owing to the plasmin and other proteases was not detected.
2. The inhibitory activities to urokinase, papain and trypsin were not found.
3 The plasminogen activator was detected in spite of the absence of the proactivator.
Additionally it was observed that the pH- and thermo-stability of plasminogen activator in the tracheobronchial secretion was similar to that of the tissue plasminogen activator with the low molecular weight found in human paranasal mucous membrane From the results obtained, it was concluded that the potential system of fibrinolysis was present in the tracheobronchial secretion although the plasminogen itself was absent