Presence of a bradykinin-like substance in pulmonary washings

Pulmonary washings were studied for the presence of bradykinin-like substances and the capacity for their formation and degradation. Bronchopulmonary lavage with saline was performed in anesthetized, exsanguinated Syrian golden hamsters with a cell yield of 99 per cent alveolar macrophages. In the presence of inhibitors of both kinin formation (hexadimethrine) and destruction (1,10-phenanthroline), immunoreactive kinin was found in bronchopulmonary lavage fluid (12.5 ng per 5 x 10(6) cells lavaged), washings of pooled macrophages (5.62 ng per 5 x 10(6) cells washed), and lysates of alveolar macrophages (3.97 ng per 5 x 10(6) cells lysed). Higher kinin concentrations were obtained by selective inhibition of kinin-destroying enzymes with phenanthroline. Inhibition of kinin formation with hexadimethrine alone rendered nearly all concentrations below the limit of detectability. These findings demonstrated that the capacity for kinin formation and degradation exists in pulmonary washings. The precise origin of this kinin and its forming and destroying enzymes (whether from the pulmonary alveolar macrophage, other sites in the bronchopulmonary tree, or plasma) is not yet known.