Intramuscular Relative Dose Response (RDR) Determination of Liver Vitamin A Stores in Rats

1991 ◽  
Vol 121 (2) ◽  
pp. 187-191 ◽  
Author(s):  
Richard D. Zachman ◽  
Xiaoming Chen
Keyword(s):  
Vitamin A ◽  
Dose Response ◽  
Liver Vitamin

Quantitative Aspects of the Urinary and Fecal Excretion of Radioactive Metabolites of Vitamin A in the Rat

1972 ◽  
Vol 50 (11) ◽  
pp. 1026-1037 ◽  
Author(s):  
R. N. Varma ◽  
G. H. Beaton
Keyword(s):  
Vitamin A ◽  
Experimental Studies ◽  
Urinary Metabolites ◽  
Fecal Excretion ◽  
Plasma Vitamin ◽  
Second Phase ◽  
Retinyl Acetate ◽  
Deficient Diet ◽  
Liver Vitamin

Urinary and fecal excretion of radioactive metabolites has been followed for 8 days (12 days in one group) in groups of rats having different initial body stores of vitamin A and given a single oral dose of 11,12-3H-retinyl acetate in oil. During the collections animals were fed a vitamin A deficient diet except for one group which was given laboratory chow throughout. At the end of the collection period animals were killed for determination of liver, kidney, and plasma vitamin A and radioactivity. Specific activities were similar in the three tissues; total liver vitamin A contents ranged from undetectable to 7700 μg. Excretion of fecal and urinary radioactivity was high initially but fell to apparently stable levels by day 8. When the combined urinary and fecal excretion was expressed in terms of the liver vitamin A equivalent (ELV), there was a gradual increase in excretion rate with the logarithm of liver vitamin A up to 150–300 μg/g liver; thereafter the rate of excretion increased more rapidly with liver stores to the highest level studied, 500–550 μg/g. In the initial phase the ELV values were 4–10 μg/day, rising to 22–24 μg/day in the second phase. These studies suggest that (a) a portion of newly absorbed vitamin A is metabolized before mixing with general body pools and probably without greatly altering the metabolism of endogenous vitamin A, (b) after equilibration of body pools, urinary excretion of radioactivity should be a useful index in experimental studies of factors affecting vitamin A metabolism, and (c) chemical determination of urinary metabolites of vitamin A is a potential index of vitamin A nutritional status.

Oral contraceptives: effect of long-term use on liver vitamin A storage assessed by the relative dose response test

1989 ◽  
Vol 49 (5) ◽  
pp. 845-848 ◽  
Author(s):  
K Amatayakul ◽  
B A Underwood ◽  
S Ruckphaopunt ◽  
R Singkamani ◽  
S Linpisarn ◽  
...  
Keyword(s):  
Vitamin A ◽  
Oral Contraceptives ◽  
Dose Response ◽  
Response Test ◽  
Liver Vitamin

The modified relative dose response (MRDR) test value predicts liver vitamin A reserves in a piglet model

2007 ◽  
Vol 21 (5) ◽  
Author(s):  
Ashley Rebecca Valentine ◽  
Rebecca L Surles ◽  
Sherry A Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Dose Response ◽  
Liver Vitamin ◽  
Modified Relative Dose Response

scholarly journals Validity of the dose-response tests for the determination of vitamin A status

2005 ◽  
Vol 82 (5) ◽  
pp. 1138-1139 ◽  
Author(s):  
Frank T Wieringa ◽  
Marjoleine A Dijkhuizen
Keyword(s):  
Vitamin A ◽  
Dose Response ◽  
Vitamin A Status

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

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