Role of phospholipids in lymphatic transport of dietary lipids in the dog

¹ Department of Physiology, University of Oregon Medical School, Portland, Oregon

The phospholipids of lymph have been measured in relation to the total lipid in 16 chronic thoracic duct fistula dogs during the postabsorptive state and following the administration of various lipid types in the diet. It was found that phospholipid transport related linearly to total lipid transport under all conditions studied, including the postabsorptive state. The percentage of lymph lipid transported as phospholipid ranged from 3 to 18% and was independent of the type of lipid fed. Depriving the animals of phospholipid precursors in the diet for as long as 90 days previously failed to alter this relationship or the total quantity of lipid transported. The total quantity of phospholipid which could be considered as having been newly synthesized as a direct result of processes underlying absorption of exogenous (dietary) fats was small and probably insignificant. The conclusion is reached that phospholipids probably do not serve as intermediates in the absorptive process, nor do they constitute important vehicles for fatty acid transport in lymph.