Effects of eicosapentaenoic and gamma-linolenic acids (dietary lipids) on pulmonary surfactant composition and function during porcine endotoxemia

Study objectives: To investigate whether a diet enriched with fish and bora ge oils, with their high polyunsaturated fatty acid (PUFA) content, alters surfactant composition and function during endotoxemia. Design: Prospective, randomized, blinded, controlled animal study. Setting: Research laboratory at a medical center. Participants: Thirty-six 15- to 25-kg, disease-free, castrated male pigs. Diets and measurements: Three groups of pigs (n = 12 per group) were fed fo r 8 days diets containing either omega-6 fatty acids (FAs) (corn oil; diet A), or omega-3 FAs (fish oil; diet B), or a combination of omega-6 ana omeg a-3 FAs (borage and fish oils; diet C). Eight of 12 pigs in each group rece ived a 0.1-mg/kg bolus of Escherichia coli endotoxin followed by a continuo us infusion (0.075 mg/kg/h). Orle lung was subsequently isolated ex vivo, a nd pressure-volume curves were measured. The contralateral lung was lavaged , and surfactant was analyzed for total and individual phospholipids and FA composition. Minimum and maximum surface tension was measured by bubble su rfactometry. Results: Pigs fed either diet B or C had increased oleic acid (C-18:1 omega -9), eicosapentaenoic acid (EPA; C-20:5 omega-3), docosahexaenoic acid (C-2 2:6 omega-3), and total omega-3 and monounsaturated FAs in their surfactant PUFA pools. The relative percentage of linoleic acid (C-18:2 omega-6) and total omega-6 FAs were significantly lower from pigs fed diets B and C comp ared with diet A Palmitic acid (C-16:0) concentrations, the primary FA in s urfactant, had a tendency to be lower in pigs fed diets B and C. There were no demonstrable effects on surfactant function or pulmonary compliance. Conclusions: Diets containing EPA or EPA and gamma-linolenic acid altered t he PUFA composition of pulmonary surfactant, but without demonstrable effec ts on surfactant function during porcine endotoxemia.