FATTY-ACID COMPOSITION OF LUNG, MACROPHAGE AND SURFACTANT PHOSPHOLIPIDS AFTER SHORT-TERM ENTERAL FEEDING WITH N-3 LIPIDS

Utilization of enteral feeding modalities may prove clinically relevan t for rapid modulation of lung phospholipid polyunsaturated fatty acid s (PUFA) that serve as substrates for the formation of vasoactive dien oic eicosanoids. We compared the effects of short-term enteral feeding with formulations enriched with either fish (n-3) or corn (n-6) oil P UFA on the fatty acid composition of rat lung, alveolar macrophage and surfactant phospholipids. The diets were infused continuously for 72 h through a surgically placed gastroduodenal feeding catheter by a syr inge pump. The n-3 PUFA derived from the fish oil enriched diet were r eadily incorporated into the phospholipid membranes of the alveolar ma crophages, lung tissue and pulmonary surfactant. The relative percenta ges of the n-3 PUFA were significantly higher and individual and total n-6 PUFA significantly lower in the macrophage, lung and surfactant p hospholipids from the n-3-supplemented rats in comparison with those p resent in the rats infused enterally with the n-6 diet or untreated, c how-fed rats (baseline). In contrast, there was a significant increase in linoleic acid (18:2n-6) without modification of arachidonic acid ( 20:4n-6) in the alveolar macrophages, lung tissue and surfactant from rats enterally receiving the n-6 diet relative to levels measured in t he rats at baseline. The results suggest that short-term continuous de livery of n-3-enriched enteral preparations can foster rapid modificat ion of membrane phospholipid PUFA composition of lung tissue, alveolar macrophages and lung surfactant. Utilization of similar infusion moda lities to deliver n-3-enriched enteral formulations may prove benefici al to critically ill or postoperative patients with persistent lung in flammation secondary to uncontrolled formation of vasoactive eicosanoi ds derived from arachidonic acid.