Detection of O2- generation and neutrophil accumulation in rat lungs after acute necrotizing pancreatitis

Polymorphonuclear neutrophils (PMNs) and PMN-derived superoxide anions (O2-) have been found to mediate acute respiratory distress syndrome (ARDS). But the evidence has been obtained only indirectly, (for example, by treatment with free radical scavengers or by measuring lipid peroxides).

We used chemiluminescence technique to measure O2- generation directly from the surface of rat lungs with necrotizing pancreatitis. Myeloperoxidase activity in the lung tissue was measured by a new chemiluminescence method to quantitate pulmonary neutrophil sequestration.

Transient bursts of chemiluminescence that reflected O2- generation were observed at the lung surface 3 to 5 hours after necrotizing pancreatitis was induced. No O2- dependent chemiluminescence was detected at the lung surfaces of the neutropenic rat made by pretreatment with polyclonal antineutrophil antibody. Myeloperoxidase activity was significantly high (mean, 1690 cell numbers/mg wet tissue) in the necrotizing pancreatitis rat lung (p < 0.005).

These data confirmed that activated neutrophils and neutrophil-derived superoxide anions were implicated in lung injury after acute severe pancreatitis.