Assessment of vitamin A metabolism with a multiple dose technique

Conference · Thu May 01 00:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:7024336

Cullum, M E; Zile, M H

A rat model has been developed to study vitamin A turnover and metabolism during physiological conditions. Body pools of vitamin A of young adult male rats were replaced with radioactive vitamin A. The effect of daily ingestion and withdrawal of 20 ..mu..g of tritiated retinyl acetate was examined on the excretion of radioactivity in urine and feces. During conditions of constant excretion, 35% of dose radioactivity was excreted daily in urine and feces, feces representing the major route of excretion. After discontinuation of daily oral administration of vitamin A, proportionally smaller amounts of radioactivity were excreted both in urine and feces on each subsequent day. Urinary excretion of radioactivity decreased at a constant rate of 0.08 micrograms per day of labeled metabolites, while fecal excretion decreased more rapidly (0.22 ..mu..g/d). Significant fecal radioactivity is associated with the processing of daily dietary vitamin A and represents the metabolism of newly absorbed and unabsorbed vitamin A. Radioactivity excreted in urine is not greatly affected by elimination of daily ingestion of vitamin A and appears to reflect the functional metabolism of this vitamin in tissues. The s.a. of circulatory retinol was similar to that of the dose, while that of liver retinyl esters was 10-30% that of the dose during the 8 day period subsequent to removal of dietary vitamin A.

• Research Organization: Michigan State Univ., East Lansing
• OSTI ID: 7024336
• Report Number(s): CONF-8604222-
• Journal Information: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:6; ISSN FEPRA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BIOLOGICAL MATERIALS
BIOLOGICAL MODELS
BIOLOGICAL WASTES
BODY FLUIDS
CARBOXYLIC ACID ESTERS
CLEARANCE
ESTERS
EXCRETION
FECES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
MATERIALS
METABOLISM
METABOLITES
ORGANIC COMPOUNDS
RATS
RETINOIC ACID
RODENTS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
URINE
VERTEBRATES
VITAMIN A
VITAMINS
WASTES