Intestinal folate binding protein (FBP) and folate absorption in the suckling rat
The folate in milk is bound to high affinity FBPs but it is unknown whether this binding affects intestinal transport of milk folate in the suckling rat. The authors examined the FBP activity of segments of the GI tract in fed and fasting states. Under fed conditions, the FBP activity in the mucosa of the stomach and proximal small intestine were similar (0.28 and 0.32 pMole folic acid binding/mg protein, N.S.). Both demonstrated less activity than the mucosa of the distal small intestine (1.31 pMole/mg protein, P < .001). A 6 hr fast produced no change in the FBP activity in the stomach or proximal small intestine but resulted in a 42% decrease in the distal small intestine (p < .01). Intestinal transport of unbound and FB-bound H/sup 3/pteryolmonoglutamate (H/sup 3/PGA) was examined in suckling rats by the intestinal loop model. Unbound H/sup 3/PGA demonstrated greater lumenal disappearance in the proximal segment of the small intestine compared to the distal segment (79% vs. 56%, P < .001) whereas the bound H/sup 3/PGA demonstrated greater lumenal disappearance in the distal segment (36% vs. 21%, p < .005). That porton of FBP activity in the distal small intestine that disappears with fasting may represent FBP absorbed from the lumen of the intestine. The FBP-bound folate in milk appears to be absorbed in the suckling rat by a mechanism that favors the distal small intestine and is different from the mechanism responsible for absorption of the unbound folate.
- Research Organization:
- Univ. of Chicago, IL
- OSTI ID:
- 5461887
- Report Number(s):
- CONF-8604222-; TRN: 86-028413
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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FOLIC ACID
INTESTINAL ABSORPTION
PROTEINS
BIOCHEMICAL REACTION KINETICS
AFFINITY
FASTING
LACTATION
MILK
RATS
SMALL INTESTINE
STOMACH
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ABSORPTION
AMINO ACIDS
ANIMALS
AROMATICS
AZAARENES
BIOLOGICAL MATERIALS
BODY
BODY FLUIDS
CARBOXYLIC ACIDS
DIGESTIVE SYSTEM
DRUGS
FOOD
GASTROINTESTINAL TRACT
HEMATINICS
HEMATOLOGIC AGENTS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INTESTINES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
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ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PTERIDINES
REACTION KINETICS
RODENTS
UPTAKE
VERTEBRATES
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550501* - Metabolism- Tracer Techniques