Effects of endotoxin on pigs prefed omega-3 vs. omega-6 fatty acid-enriched diets

We investigated in a porcine model whether omega-3 fatty acids modify the physiological response to sepsis. For 8 days, 16 male pigs were fed a diet containing 18% fat by weight enriched with either omega-3 or omega-6 fatty acids (FA). A group of six pigs receiving their regular diet served as controls. The omega-3 FA-supplemented pigs had elevated levels of omega-3 FA in their serum-free FA, serum phospholipid (PL), and platelet PL levels compared with either of the other groups. On the ninth day, the unanesthetized pigs were injected with 0.3 mg/kg of endotoxin (Escherichia coli) intravenously. The animals had a significant decrease in their arterial O2 pressure (PaO2) [from 84.4 +/- 6.8 (SD) to 64 +/- 9.4, and from 83.1 +/- 7.2 to 55.9 +/- 6.3 mmHg in the omega-6 FA and regular diet groups, respectively]. The PaO2 did not decrease in the omega-3 FA pigs. The omega-3 FA group had significantly lower pulmonary vascular resistance (541 +/- 205 dyn.s.cm-5) 20 min after endotoxin compared with either the omega-6 FA or regular diet groups (797 +/- 233 and 1,102 +/- 552 dyn.s.cm-5, respectively) and more normal blood pressure compared with the other two groups. Plasma thromboxane (Tx) B2 and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) levels were lowest in the omega-3 FA diet group and highest in the regular diet group.(ABSTRACT TRUNCATED AT 250 WORDS)