Gastroenterology

Gastroenterology

Volume 60, Issue 6, June 1971, Pages 997-1007
Gastroenterology

Isolation of the Aqueous Phase of Human Intestinal Contents During the Digestion of a Fatty Meal

https://doi.org/10.1016/S0016-5085(71)80027-6Get rights and content

Commonly used methods for isolating the aqueous phase of human intestinal contents after a fatty meal involve heating pooled samples of intestinal contents to 70 C to abolish lipolysis and spinning the heated sample at 100,000 g for 15 to 18 hr to separate the aqueous phase from the emulsion droplets. We found that this method introduces artifacts. (1) Heating batches of intestinal contents in a 70 C water bath increases free fatty acid markedly and alters phospholipid composition. (2) Spinning intestinal contents creates concentration gradients, which makes random sampling misleading because of the heterogeneous composition of the infranatant solution. A method is described which isolates the aqueous phase of intestinal contents by filtration through two series of Millipore filters. Clogging of filters is avoided by feeding a protein-free test meal. A 10-ml sample of intestinal contents can be passed within 30 sec through the first series of filters (mean pore diameter: 30,000; 8,000; 4,500; and 3,000 A). Release of free fatty acid in the resulting 3000-A filtrate is greatly reduced, because more than 95% of the triglyceride of intestinal contents is removed. Most of the turbidity in the 3000-A filtrates is removed when these filtrates are passed through the second series of filters (2200 and 1000 A). The resulting 1000-A filtrate is optically clear, or slightly turbid, and contains 89.7% of the bile salts of unfiltered intestinal contents. Experiments in which intestinal contents were labeled with radioactive cholesterol and bile salt indicate that the micellar association between these two lipids is not disrupted by filtration. Intestinal contents from the duodenojejunal junction of 9 normal subjects after a test meal contained 669 ± 106 (mean ± SD) μg of trypsin per ml and 8.6 ± 1.4 mm bile salts; the aqueous phase (1000-A filtrate) contained 7.7 ± 1.3 mm bile salts and 10.8 ± 3.5 mm free fatty acid.

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  • Cited by (0)

    This study was supported by Research Grant CA 04320 and by Training Grant AM 05099 from the National Institutes of Health. Part of this work was conducted in the Clinical Research Center which is supported by Grant RR-37 from the National Institutes of Health.

    The authors are indebted to Drs. C. E. Rubin, M. A. Wells, W. M. Weinstein, J. M. Dietschy, and J. A. Glomset for enlightenment and encouragement. Miss Janet Wilson was our technical assistant.

    1

    Dr. Saunders is the recipient of a Research Career Development Award.

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