Hemodynamic effects of oleic acid in newborn lambs: role of arachidonic acid metabolites.

Oleic acid injection produces acute lung injury and pulmonary hypertension in adult animals. In other types of acute lung injury, such as that caused by E. coli endotoxin, metabolites of arachidonic acid are important mediators of pulmonary hypertension. In order to understand the hemodynamic response of newborn animals to oleic acid injection and the contribution of arachidonic acid metabolites to that response, we injected oleic acid into awake, chronically instrumented newborn lambs. The hemodynamic response of lambs to injections of oleic acid alone was compared to their response after pretreatment with either FPL57231, a putative leukotriene receptor antagonist, or indomethacin, a cyclooxygenase synthesis inhibitor. Oleic acid caused acute pulmonary hypertension associated with an increase in protein-rich lung lymph fluid. Systemic hemodynamic effects were variable. FPL57231 completely blocked the oleic acid-induced pulmonary hypertension while indomethacin significantly attenuated the response. Therefore, metabolites of arachidonic acid metabolism appear to be important mediators of oleic acid-induced pulmonary hypertension in newborn lambs.