Characteristics of neutrophil influx in rat lungs following fecal peritonitis.

Neutrophil accumulation in rat lungs during fecal peritonitis was estimated by the increase in myeloperoxidase content. The oxidative response of lung neutrophils was monitored as the increase in low-level chemiluminescence from intact lungs, before and after stimulation by phorbol myristate acetate (PMA). Myeloperoxidase activity increased 20-fold within 6 h of the surgical procedure, declining over the next 10 h to 12 times control. There was no significant increase over controls in either bronchoalveolar lavage protein or spontaneous chemiluminescence unless neutrophils were stimulated by PMA. When neutrophils were stimulated with PMA, lung chemiluminescence was not proportional to neutrophil content. The oxidative response increased as sepsis progressed from 51 +/- 4.5 cps/pair lungs in controls to 410 +/- 204 at 16 h after surgery, even though at that time point myeloperoxidase content had begun to decrease. The oxidative response of bronchoalveolar lavage cells was threefold greater in 16-h septic rats than in controls.