METHODS FOK STUDY OF FAT ABSORPTION 127 



a. Method of Irwin, Steenbock, and Templin. 611 In this procedure only 

 adult male rats, four to seven months of age and weighing 200 to 400 g., 

 were used, following a forty-eight hour fast prior to the absorption tests. 

 The rats were lightly anesthetized with ether, and the test fat was delivered 

 directly into the stomach, by means of a 2 ml. syringe connected with a 

 rubber catheter. Although doses of several amounts were tested, a stand- 

 ard 1.5 ml. dose was used in the tests with various fats. Different groups 

 of rats were sacrificed by decapitation at several periods after feeding, and 

 the intact gastrointestinal tract was removed. The stomach, cecum, and 

 the intestine, divided into two sections, were all filled with distilled water, 

 and the washings were emptied into beakers after ten minutes; this was 

 followed by the introduction of petroleum ether into the several portions 

 of the intestinal tract for a second ten-minute interval. The stomach and 

 cecum were then opened and washed thoroughly with a jet of water and 

 petroleum ether, while the intestine was stripped manually to remove the 

 last trace of food. After extraction of the fat from the aqueous washings 

 with additional petroleum ether, the combined petroleum ether extracts 

 were dried with anhydrous sodium sulfate, the extract was filtered, and the 

 petroleum ether was removed in a vacuum oven. When this technic was 

 tested on rats which were sacrificed immediately after the feeding of the 

 fat, recoveries of 97 to 98% were obtained. Since these workers could 

 demonstrate no relationship between absorption rate on the one hand, and 

 body weight, surface area, or length of the intestines on the other hand, 

 the results were expressed in percentage of administered fat absorbed in a 

 given time. 



b. Method of Deuel, Hallman, and Quon. 612 This procedure is quite 

 similar in many respects to that of Irwin et al. 6n However, because of the 

 adjustment of the dosage to the size of the animal, it was possible to use 

 the procedure for animals with a somewhat wider range of body weights. 

 The animals were not anesthetized for the fat feeding, but were given amy- 

 tal just before being sacrificed, at the end of the absorption period. At the 

 termination of the test period, after the rat was under the influence of the 

 anesthetic, the gastrointestinal tract was carefully removed; the fat re- 

 maining in the gastrointestinal tract was removed by flushing it with 

 petroleum ether under some positive pressure. This was accomplished by 

 attaching to the esophagus a syringe containing the ether and connected 

 with a large blunt needle. Pressure was applied manually to force the 

 ether into the gastrointestinal tract at a rate sufficient to produce the de- 



611 M. H. Irwin, H. Steenbock, and V. M. Templin, J. Nutrition, 12, 85-101 (1936). 

 812 H. J. Deuel, Jr., L. F. Hallman, and S. Quon, J. Biol. Chem., 128, xix-xx (1939). 



