SELECT DIETARY FATTY-ACIDS ATTENUATE CARDIOPULMONARY DYSFUNCTION DURING ACUTE LUNG INJURY IN PIGS

We examined the effect of substituting linoleic acid (LA) with eicosap entaenoic acid (EPA) and gamma-linolenic acid (gamma-LA), precursors o f trienoic and monoenoic eicosanoids, respectively, on acute lung inju ry (ALI). Three groups (n = 8/group) of pigs were fed enteral diets co ntaining LA (diet A), EPA (diet B), or EPA + gamma-LA (diet C) for 8 d ays. ALI was then induced with a 0.1 mg/kg bolus of Escherichia coil e ndotoxin followed by a continuous infusion for 4 h (0.075 mg . kg(-1). h(-1)). Pulmonary arterial and capillary wedge pressures, cardiac ind ex (CI), arterial blood gases, arterial O-2 content, and plasma thromb oxane 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 del ivery at 20 min, an improvement that was sustained throughout the 4-h study period with the EPA + gamma-LA-enriched diet only. This improvem ent 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 decrease d TxB(2) levels in animals fed diets B and C correlate with an attenua tion in the increase in pulmonary vascular resistance that was observe d at 20 min after endotoxin infusion in animals fed diet A. These data suggest that specialized enteral diets enriched in EPA + gamma-LA imp rove gas exchange and O-2 delivery, presumably in part through a modif ication of TxB(2) production with a decrease in pulmonary vascular res istance and an increase in CI, during ALI.