Cholesterol esterase activity of human intestinal mucosa
It has been suggested that cholesterol absorption in humans is dependent on bile acid pool composition and that expansion of the cholic acid pool size is followed by an increase of the absorption values. Similar observations were reported in rats. In the present study, therefore, the authors investigated some general properties of human intestinal cholesterol esterase, with particular emphasis on the effect of bile acids on this enzymatic activity. Twenty-nine segments of small intestine were taken during operations; the enzymatic activity was studied by using mucosal homogenate as a source of enzyme and oleic acid, cholesterol, and UC-labeled cholesterol as substrates. The time-activity relationship was linear within the first two hours; optimal pH for esterification ranged between 5 and 6.2. There was little difference between the esterifying activity of the jejunal and ileal mucosa. Esterification of cholesterol was observed with all the investigated fatty acids but was maximal with oleic acid. Bile acids did not affect cholesterol esterase activity when present in the incubation mixture at 0.1 and 1.0 mM; the enzymatic activity, however, was significantly inhibited when bile acids were added at 20 mM. In conclusion, this study has shown that the human intestinal mucosa possesses a cholesterol esterase activity; at variance with the rat, however, the human enzyme does not seem to be stimulated by trihydroxy bile acids.
- Research Organization:
- Universita di Modena, Italy
- OSTI ID:
- 6294144
- Journal Information:
- Dig. Dis. Sci.; (United States), Vol. 11
- Country of Publication:
- United States
- Language:
- English
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INTESTINAL ABSORPTION
MUCOUS MEMBRANES
ENZYME ACTIVITY
CARBON 14 COMPOUNDS
ESTERASES
RATS
SMALL INTESTINE
ABSORPTION
ANIMALS
BODY
CHEMICAL REACTIONS
DIGESTIVE SYSTEM
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GASTROINTESTINAL TRACT
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LABELLED COMPOUNDS
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551001* - Physiological Systems- Tracer Techniques