Influence of Food Fat on the Constitution of the Phospholipids.

Abstract

In the course of an investigation concerning the mechanism of fat absorption, it was thought that possibly the phospholipids of the intestinal mucosa are intermediary products in the process of fat resynthesis from the absorbed fatty acids and glycerol. If this be true, during the absorption of fat the constituent fatty acids of the phospholipids in the mucosa must consist, in part at least, of the fatty acids of the ingested fat. In order to test this idea it was decided to see if the absorption of such fats as cod liver oil and cocoanut oil (which are characterized by high and low degrees of unsaturation, respectively) produces a change in the iodine absorption value (I.N.) of the phospholipid fatty acids in the absorbing mucosa. Later the investigation was extended to include a study of the effect of fat absorption and of different continued diets on the constitution of the phospholipids of the intestinal and skeletal muscles and of the liver.

The experimental plan was as follows: To one of a pair of cats which had been kept on the same diet for 2 weeks or longer either cod liver oil or cocoanut oil was administered by stomach tube; some time later (usually 5-7 hours) the animal was killed. The other cat was killed in a post-absorptive state to serve as a control. The mucosa and the muscle of the small intestine were separated; the muscles of one hind leg were used to typify skeletal muscle. The lipids were extracted with hot alcohol and the phospholipids were isolated and purified by acetone precipitation from ether solution, according to the method of Bloor. 1 After saponification of the phospholipids, the weight and I.N. of the constituent fatty acids were determined.