The Intestinal Absorption of Phospholipids in the Rat

Summary. The intestinal absorption of phospholipids has been studied after feeding rats with lymph fistulas phospholipids containing A. oleic acid‐l‐14C, B. palmitic acid‐l‐14C and 14C‐glycerol or C. palmitic acid‐l‐14C and 32P. The recoveries of the absorbed radioactivity in the thoracic duct lymph was about the same whether 14C‐labelled palmitic acid or 14C‐labelled oleic acid was incorporated into the phospholipids administered. The major part of the activity in the lymph lipids was associated with the glycerides, but after feeding, phospholipids containing either labelled palmitic acid or labelled oleic acid, a significantly greater amount of activity was obtained in the phospholipids than after feeding these acids as glycerides or as the free acid. A small amount of the lymph glyceride glycerol is derived from the fed phospholipid glycerol suggesting a synthesis from a partial glyceride. The relative specific activity of the lymph phospholipid glycerol was about 30 per cent indicating that a significant amount of the fed phospholipids had been absorbed without previous splitting of the glycerol phosphate linkages. The experiments with 32P‐labelled phospholipids support this suggestion. The experimental data thus indicate that a very extensive hydrolysis of the phospholipids takes place during the absorption process, but also that complete hydrolysis does not necessarily occur.