STUDY ON THE FAT ABSORPTION AND TRANSPORTATION INTO INTESTINAL LYMPH OF RATS

Differences in the Absorption of Saturated and Unsaturated Long Chain Fatty Acids and the Role of Intestinal Alkaline Phosphatase

Abstract

The present experiments were carried out to compare the metabolic differences between saturated and unsaturated long chain fatty acids in small intestinal mucosa and to determine the effect of fatty acid absorption and transportation on the activity of intestinal alkaline phosphatase.
The absorption and transportation of fats were studied in male Wistar rats provided with intestinal lymph fistula. Mixed micellar solutions of fatty acids were administered into the duodenum of rats and absorbed fat and alkaline phosphatase activity were studied in intestinal lymph.
The absorption and transportation of linoleic acid into intestinal lymph exceeded that of palmitic acid. Puromycin, an inhibitor of protein synthesis, decreased the absorption and transportation of linoleic acid, but did not change that of palmitic acid. Intestinal alkaline phosphatase activity was enhanced in proportion to the degree of fat absorption and puromycin prevented the rise in lymph alkaline phosphatase activity after the infusion of micellar solution of linoleic acid. However, palmitic acid-induced increase in lymph alkaline phosphatase activity was not affected by puromycin.
L-phenylalanine, a specific inhibitor of intestinal alkaline phosphatase, decreased the activity of brush border alkaline phosphatase of rat jejunum and prevented the rise in lymph alkaline phosphatase during fat absorption. The absorption and transportation of linoleic acid was also decreased by L-phenylalanine.
Therefore, different metabolic pathways were suggested between unsaturated and saturated long chain fatty acid in intestinal mucosa. Furthermore intestinal alkaline phosphatase may play an important role in the transport of long chain fatty acid into intestinal lymph.