We have examined various biochemical parameters of
pulmonary inflammation in experimental animals. Intrabronchial instillation of
glucose oxidase-
glucose (GO/G) to produce
oxidants or formylated norleu-
leu-phe (FNLP) or
phorbol myristate acetate (PMA) as leukocytic stimuli induced severe acute
pulmonary injury in New Zealand white rabbits. PMA also induced
inflammation when administered intravenously. Each stimulus induced transudation of
protein from the vascular space into the pulmonary tissues, and an influx of leukocytes during the 4-6 h period of the experiment. Pathophysiologic changes were measured by
edema formation (transudation of 125I-
bovine serum albumin), and histologic examination. Biochemical analysis was performed by measuring concentrations of potentially injurious agents in bronchoalveolar lavage (BAL) fluid. Increased
acid protease and
myeloperoxidase levels were found in the BAL fluid after administration of either of the stimuli. Evidence of
oxidant generation in vivo was obtained in two different ways. In the first, specific activities for
catalase were measured in the BAL fluid in the presence or absence of 3-amino, 1,2,4
triazole (AT), injected at intervals before obtaining BAL fluid. In the presence of AT, specific activities for
catalase dropped to 0.22 after a double instillation of FNLP and to 0.15 in the presence of GO/G. In neutrophil-depleted FNLP animals,
catalase was not greatly inhibited by AT (sp act 0.90). In the second, intracellular levels of total
glutathione (GSH +
GSSG) in whole lung tissue and alveolar macrophages decreased when stimuli of neutrophils were administered. Intrabronchially instilled PMA, e.g., caused a drop of
glutathione in whole lung tissue from the control value of 2.3 mumol GSH equivalent/100 mg dry wt to 0.54 mumol GSH equivalent/100 mg dry wt at 4 h. Neutrophil depletion and
superoxide dismutase protected from this effect. From these results, we conclude that O-2 or its metabolites can initiate severe
pulmonary injury as shown by the effect of GO/G and that, during development of
pulmonary injury, stimulated neutrophils generate
oxidants and release
proteolytic enzymes into the surrounding tissues.