The Effect of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) on the Uptake, Distribution and Excretion of a Single Oral Dose of [11,12-3H]Retinyl Acetate and on the Vitamin A Status in the Rat

1985 ◽  
Vol 115 (6) ◽  
pp. 759-771 ◽  
Author(s):  
Helen Håkansson ◽  
Ulf G. Ahlborg
Keyword(s):  
Vitamin A ◽  
Oral Dose ◽  
Single Oral Dose ◽  
Retinyl Acetate ◽  
Vitamin A Status ◽  
Tetrachlorodibenzo P Dioxin

Compartmentation of "Endogenous" and Newly Absorbed Vitamin A in the Rat

1974 ◽  
Vol 52 (3) ◽  
pp. 583-589 ◽  
Author(s):  
D. L. Yeung ◽  
M. J. Veen-Baigent
Keyword(s):  
Vitamin A ◽  
Oral Dose ◽  
Single Oral Dose ◽  
Aqueous Phase ◽  
Dilution Effect ◽  
Fecal Excretion ◽  
Retinyl Acetate ◽  
Per Se ◽  
Retinyl Esters

Urinary and fecal excretion of 3H-labelled metabolites of vitamin A was followed in rats given a single oral dose of 3H-11,12-retinyl acetate (RA), followed 8 days later by a dose of non-labelled RA. The level of radioactivity in urine and feces fell to a more consistently lower level by the 8th day after administration of 3H-RA but no dilution effect was seen 24 h after administration of non-labelled RA. Dilution of 3H-metabolites became gradually evident and was statistically significant 4–6 days after the administration of non-labelled RA. The results are considered to be compatible with the theory that newly absorbed vitamin A does not immediately mix with endogenous vitamin A, but is temporarily metabolized (and stored) in a separate compartment. Plasma aqueous phase contained considerable radioactivity not due to vitamin A per se; it likely represented metabolites prior to excretion. It is doubtful these originated in the liver since all hepatic radioactivity was due to retinol and retinyl esters.

Vitamin A (retinol) status in the rat after a single oral dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin

1979 ◽  
Vol 42 (4) ◽  
pp. 265-274 ◽  
Author(s):  
Tuula Thunberg ◽  
Ulf G. Ahlborg ◽  
H�kan Johnsson
Keyword(s):  
Vitamin A ◽  
Oral Dose ◽  
Single Oral Dose ◽  
Tetrachlorodibenzo P Dioxin

scholarly journals Vitamin A Absorption Determined in Rats Using a Plasma Isotope Ratio Method

2020 ◽  
Vol 150 (7) ◽  
pp. 1977-1981 ◽  
Author(s):  
Michael H Green ◽  
Joanne Balmer Green
Keyword(s):  
Vitamin A ◽  
Oral Dose ◽  
Isotope Ratio ◽  
Cholesterol Absorption ◽  
Absorption Efficiency ◽  
Intravenous Dose ◽  
Ratio Method ◽  
Sprague Dawley ◽  
Retinyl Acetate ◽  
Dose Fraction

ABSTRACT Background Better methods are needed for determining vitamin A absorption efficiency. Objective Our objective was to measure vitamin A absorption in rats by adapting a plasma isotope ratio method previously used to determine cholesterol absorption. Methods Male Sprague-Dawley rats [n = 14; 340 ± 16 g (mean ± SD)] received an oral tracer dose of [3H]retinyl acetate in oil plus an intravenous dose of [14C]vitamin A–labeled lymph prepared in a donor rat that had received [14C]retinyl acetate intraduodenally. Blood samples were collected on days 1, 2, 3, 6, 9, and 12, and plasma was analyzed for 3H and 14C; vitamin A absorption was calculated for each sample as (fraction of oral dose/fraction of intravenous dose) × 100. Radioactivity was also measured in feces and urine collected as pools on days 3, 6, 9, and 12 and in liver and remaining carcass on day 12. Results Vitamin A absorption calculated as the plasma isotope ratio was >100% on day 1, 78% ± 5% on day 6, 76% ± 5% on day 9, and 74% ± 5% on day 12; fitting the data to an exponential function plus a constant predicted an absorption of 75% by day 14. Recovery of the oral dose in feces (day 0 to day 6) was low (6.2% ± 0.84%, n = 10) and the mean isotope ratio in day 9–12 urine pool was lower than that in plasma. Conclusions The plasma isotope ratio holds promise for estimating vitamin A absorption, but additional work is needed to determine how long studies need to be and if the doses should be administered simultaneously. For application of this method in humans, artificial chylomicrons labeled with a stable isotope of retinyl acetate could be used for the intravenous dose, with a different isotope required for the oral dose.

scholarly journals Plasma kinetics of an oral dose of [2H4]retinyl acetate in human subjects with estimated low or high total body stores of vitamin A

1998 ◽  
Vol 68 (1) ◽  
pp. 90-95 ◽  
Author(s):  
M J Haskell ◽  
M A Islam ◽  
G J Handelman ◽  
J M Peerson ◽  
A D Jones ◽  
...  
Keyword(s):  
Vitamin A ◽  
Oral Dose ◽  
Human Subjects ◽  
Retinyl Acetate ◽  
Plasma Kinetics ◽  
Total Body ◽  
Kinetics Of

Divergent Effects of Excess Dietary Vitamin A on Alimentary Cholesterolemia in Cockerels of Different Genetic Backgrounds

1975 ◽  
Vol 53 (2) ◽  
pp. 256-263
Author(s):  
Bill Woodward ◽  
B. E. March
Keyword(s):  
Vitamin A ◽  
Oral Dose ◽  
Single Oral Dose ◽  
New Hampshire ◽  
Dietary Cholesterol ◽  
The Other ◽  
Dietary Vitamin ◽  
White Leghorn ◽  
Variable Effect ◽  
Large Load

The variable effect of excessive vitamin A intake on alimentary cholesterolemia was investigated in cockerels of strains of White Leghorns and New Hampshires. With the New Hampshire cockerels, the feeding of 0.5% of dietary cholesterol resulted in greater cholesterolemia when the diet contained 1 700 I.U. of vitamin A per kilogram than when it contained 22 000 I.U. of vitamin A per kilogram. With the White Leghorn cockerels, on the other hand, cholesterolemia was enhanced with the higher level of dietary vitamin A. Absorption of a single oral dose of cholesterol was increased in birds of both breeds when vitamin A had been given previously by injection. In the White Leghorn cockerels the percentage of newly absorbed cholesterol in the hepatic pool was reduced by vitamin A administration, whereas in the New Hampshire cockerels the percentage was increased. It was concluded that excess vitamin A may have divergent effects on alimentary cholesterolemia in chickens of different genetic backgrounds as a result of opposite effects on the liver–blood ratio of a large load of cholesterol.

scholarly journals Studies on metabolism of vitamin A. The effect of vitamin A status on the secretion rates of some steroids into the ovarianvenous blood of pregnant rats

1971 ◽  
Vol 122 (2) ◽  
pp. 235-239 ◽  
Author(s):  
J. Ganguly ◽  
G. S. Pope ◽  
S. Y. Thompson ◽  
Joyce Toothill ◽  
J. D. Edwards-Webb ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Vitamin A ◽  
Venous Blood ◽  
Retinyl Acetate ◽  
Deficient Diet ◽  
Pregnant Rats ◽  
Vitamin A Status ◽  
Previous Demonstration ◽  
Secretion Rates ◽  
Steroid Dehydrogenase

1. Rats raised on a vitamin A-deficient diet supplemented with either retinyl acetate or retinoic acid were mated and became pregnant. 2. The rates of secretion of progesterone, 20α-hydroxypregn-4-en-3-one, oestradiol-17β and oestrone into the ovarian-venous blood of rats in these two groups were measured on days 9 and 15 of pregnancy. 3. Rates of secretion of progesterone and 20α-hydroxypregn-4-en-3-one, both on days 9 and 15, were lower for the rats given retinoic acid. No such differences were found in ovarian oestrogen secretion. 4. The implications of these results are discussed in the light of the previous demonstration that the activity of ovarian 3β-hydroxy-Δ5-steroid dehydrogenase was markedly less in pregnant rats given retinoic acid.

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