Select dietary fatty acids attenuate cardiopulmonary dysfunction during acute lung injury in pigs

We examined the effect of substituting linoleic acid (LA) with eicosapentaenoic acid (EPA) and gamma-linolenic acid (gamma-LA), precursors of trienoic and monoenoic eicosanoids, respectively, on acute lung injury (ALI). Three groups (n = 8/group) of pigs were fed enteral diets containing LA (diet A), EPA (diet B), or EPA + gamma-LA (diet C) for 8 days. ALI was then induced with a 0.1 mg/kg bolus of Escherichia coli endotoxin followed by a continuous infusion for 4 h (0.075 mg . kg(-1). h(-1)). Pulmonary arterial and capillary wedge pressures, cardiac index (CI), arterial blood gases, arterial O-2 content, and plasma thromboxane B-2 (TxB(2)) were measured. Arterial PO2 decreased at 20 min in animals fed diet A. This change was attenuated with diets B and C. The EPA- and EPA + gamma-LA-enriched diets attenuated the fall in O-2 delivery at 20 min, an improvement that was sustained throughout the 4-h study period with the EPA + gamma-LA-enriched diet only. This improvement in O-2 delivery was due not only to the improved arterial PO2, but also to the maintenance of CI at 20 min in animals fed diets B and C and throughout the 4-h study period in animals fed diet C. At 4 h, TxB(2) increased 10-fold over baseline in animals fed diet A, whereas in animals fed diets B and C the increase was only 3-fold. These decreased TxB(2) levels in animals fed diets B and C correlate with an attenuation in the increase in pulmonary vascular resistance that was observed at 20 min after endotoxin infusion in animals fed diet A. These data suggest that specialized enteral diets enriched in EPA + gamma-LA improve gas exchange and O-2 delivery, presumably in part through a modification of TxB(2) production with a decrease in pulmonary vascular resistance and an increase in CI, during ALI.