UPTAKE AND METABOLISM OF SPHINGOLIPIDS IN ISOLATED INTESTINAL LOOPS OF MICE

Sphingolipids are found in all eukaryotic organisms. However, little i s known about the digestion, uptake and subsequent metabolism of these constituents of food. In this study, radiolabeled sphingolipids were placed in isolated intestinal segments of female CF1 mice, and the met abolism and distribution of the radiolabel were followed. Most of the sphingomyelin was degraded to ceramide and other products in all regio ns of the intestine, and increasing amounts of several [H-3]. labeled sphingolipids appeared in the tissues. Small amounts of the radiolabel disappeared from the intestinal loops and appeared in liver within th e first 30 to 60 min implying that neither intact sphingomyelin nor it s metabolites are transported very efficiently from the intestine to o ther organs. There were different degrees of uptake and metabolism of sphingomyelin, [4,5-H-3-sphinganyl]ceramide and [H-3]sphingosine. The [JH]sphingomyelin was also administered by gavage and the appearance a long the intestine measured. After 90 min, 12% was found in the cecum and colon. These results establish that some of the sphingomyelin that enters the gastrointestinal tract is hydrolyzed and taken up by the i ntestine, with the lipid backbone being degraded or reutilized for com plex sphingolipid synthesis; however, at least a portion passes into t he large intestine. The appearance of bioactive compounds throughout t he gastrointestinal tract may alter the behavior of intestinal cells.