Studies on the Phospholipid Metabolism of the Intestinal Mucosa during Fat Absorption

Abstract

The incorporation of radioactivity into individual phospholipid of rat intestinal mucosa at various intervals after the administration of inorganic P³² into the intestinal lumen during fat absorption was studied. Within one hour after the P³² administration, the specific activity of the total phospholipids from the intestinal mucosa was much higher than that from either the liver or blood plasma, and the specific activity as well as the relative specific activity of the total phospholipids from the intestinal mucosa was higher in the fat-fed group than in the fasted group. Little difference was observed, between the fasted and fat-fed groups, in the specific activity and the relative specific activity of phosphatidic acid, which were exceedingly higher than those of phosphatidyl-choline, -ethanolamine and -inositol, at any period after the P³² administration. The specific activity as well as the relative specific activity of phosphatidyl choline was much higher in the fat-fed group than in the fasted group. The data presented are in good agreement with the results obtained by Gurr et al., suggesting that main resynthesis of triglycerides in the intestinal mucosa during fat absorption may pass through monoglyceride, but not through phosphatidic acid. It appears that the intestinal mucosa is very similar to the liver as far as the metabolic behavior of lecithin and cephalin is concerned. Some considerations on phospholipid metabolism in the intestinal mucosa and lumen are discussed.