In vivo kinetics of intestinal absorption of riboflavin in rats

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Journal of Nutrition; (USA)

OSTI ID:5894544

Feder, S; Daniel, H; Rehner, G ^[1]

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1. Univ. of Giessen (Germany, F.R.)

To investigate absorption kinetics of riboflavin under in vivo conditions, with blood and lymph circulation intact, the small intestine of anesthetized rats was perfused with ({sup 14}C)riboflavin in a concentration range between 0.31 and 10.00 mumol/L. Apart from the uptake of riboflavin from the perfusate, passage of the vitamin into the portal (vena portae) and peripheral (vena femoralis) blood was determined. The absorption proved to be a dual process: at low substrate concentrations (less than 2 mumol/L) a saturable component predominated; at higher concentrations simple diffusion was found to be the prevailing uptake mechanism. The apparent transport constant of the saturable component was calculated to be 0.38 mumol/L. ({sup 14}C)flavin concentrations in the portal and peripheral blood were estimated as a function of the riboflavin concentration of the perfusion media. The dual character of the absorption was reflected by the portal blood flavin levels. Due to the high retaining and equalizing capacity of the liver, the ({sup 14}C)flavin level of the peripheral blood was relatively low and obeyed saturation kinetics. Constants of elimination, determined by pharmacokinetic calculations, were different for the two blood compartments but independent of the concentration of riboflavin in the perfusion media.

• OSTI ID: 5894544
• Journal Information: Journal of Nutrition; (USA), Vol. 121:1; ISSN 0022-3166
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
RIBOFLAVIN
INTESTINAL ABSORPTION
CARBON 14 COMPOUNDS
IN VIVO
METABOLISM
PERFUSED TISSUES
RATS
SMALL INTESTINE
TRACER TECHNIQUES
ABSORPTION
ANIMAL TISSUES
ANIMALS
BODY
DIGESTIVE SYSTEM
GASTROINTESTINAL TRACT
INTESTINES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
ORGANS
RODENTS
TISSUES
UPTAKE
VERTEBRATES
VITAMIN B GROUP
VITAMINS
550501* - Metabolism- Tracer Techniques