Protective effect of a selective leukotriene antagonist in endotoxemia in the rat

The role of lipoxygenase metabolites as inflammatory mediators in endotoxic shock remains uncertain. In the present study, the effects of a selective leukotriene (LT) D4/LTE4 antagonist, LY171883, 1-[2-hydroxy-3-propyl-4-[4-(1H-tetrazol-5-YL)-butoxy]-phenyl ethanone], on endotoxin-induced sequelae in the rat were assessed. LY171883 was given as a bolus (30 mg/kg i.v.) 10 min before Salmonella enteritidis endotoxin (40 mg/kg) in ketamine-anesthetized (200 mg/kg i.m.) rats, followed by an infusion (10 mg/kg/hr) starting at 30 min postendotoxin. Carotid artery blood pressures were determined at 10 min before and at intervals up to 240 minutes postendotoxin administration. Compared to shocked vehicle controls LY171883 attenuated (analysis of variance, P less than .02) the initial (0-30 min), but not the later, endotoxin-induced hypotension. LY171883 prevented completely (analysis of variance, P less than .001) the neutropenia (0-180 min), but not the thrombocytopenia induced by endotoxin. Hemoconcentration resulting from endotoxemia was reduced by LY171883 compared to the vehicle control group (P less than .02). These data demonstrate that this LTD4/LTE4 antagonist has significant salutary actions in endotoxemia and suggest that LTs may contribute to some endotoxin-induced sequelae.