Influence of parenteral nutrition on phospholipid metabolism in posttraumatic rat lungs

In the current investigation, we studied two groups of rats--one group supplied exogenous phospholipid precursors (carbohydrate plus fat emulsion group) and the other given only calories (carbohydrate group)--to evaluate the effects on surfactant composition by normocaloric alimentation, using a hypovolemic-traumatic shock model. The total phospholipid (PHL) contents of lung tissue were similar in both groups. However, we found differences in the dipalmitoylphosphatidylcholine fraction (DPPC--the most important component of surfactant material) in both lung tissue and lavage fluid. With lipid emulsion, there was an increased fraction of saturated lecithins (mainly DPPC) both in lung tissue and lavage fluid, similar to former studies with hypocaloric alimentation. In this model, those findings suggest that the PHL pattern does not depend on the quantity of caloric supply, but, rather, on the infusion composition. The enhanced DPPC content is further reflected in improved surfactant status: lipid in parenteral nutrition (PN) may exert a direct salutary effect on lung mechanics.