Oleic acid-induced injuries in the guinea-pig. Effects of allopurinol on cell dynamics, erythrocyte-catalase and uric acid plasma levels.

1. Oleic acid was used to produce adult respiratory distress syndrome-like pulmonary microvascular injuries. The resulting injuries have previously indicated involvement of accumulating neutrophils (Hultkvist et al. 1988). Activated neutrophils release oxygen free radicals that may be possible to detect in the plasma. 2. The dynamics of neutrophils and platelets were studied in the guinea-pig after oleic acid-induced injury (0.03 ml/kg per 10 min). 3. As an indication of oxygen free radical activity, plasma levels of uric acid and red blood cell (RBC)-catalase, were analysed. 4. Allopurinol (10 mg/kg, i.p.) was given prior to oleic acid infusion to block the production of uric acid. 5. The neutropenia, in contrast to the thrombocytopenia seen at 15 min, was significantly inhibited in the allopurinol pretreated group compared with oleic acid and vehicle alone. 6. The blood plasma concentration of uric acid was significantly elevated after 15 min from start of experiment. Allopurinol pretreatment significantly reduced the uric acid plasma level. 7. The RBC catalase activity did not change with time within or between any groups. 8. The results indicate that sequestration of activated neutrophils in the microvasculature are to some extent oxygen free radical dependent.