EFFECTS OF OXYGEN RADICALS ON CYSTEINYL LEUKOTRIENE METABOLISM AND PULMONARY CIRCULATION IN YOUNG-PIGS

The effects of oxygen radicals, generated by the hypoxanthine-xanthine oxidase (XO) system, on pulmonary circulation and release of cysteiny l-containing leukotrienes (LTs) were studied in pigs after XO infusion into the right atrium. A 2.3-fold increase in pulmonary vascular resi stance (PVR) (p < 0.05 vs. baseline) and a 2.1-fold increase in LT rel ease (p < 0.05 vs. baseline) was observed. Pretreatment with indometha cin and allopurinol attenuated the vascular response (p < 0.01 and p < 0.05 vs. XO), and the LT release was inhibited by allopurinol and cat alase (p < 0.01 and p < 0.02 vs. XO). We conclude that oxygen radicals stimulate lipoxygenase metabolism. This coincides with the observed i ncrease in PVR, however, no causal relationship can be derived from th e data presented.