利用血浆同位素比法测定大鼠维生素 A 吸收。

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

机构信息

Department of Nutritional Sciences, College of Health and Human Development, The Pennsylvania State University, University Park, PA, USA.

出版信息

J Nutr. 2020 Jul 1;150(7):1977-1981. doi: 10.1093/jn/nxaa092.

DOI:10.1093/jn/nxaa092

PMID:32271921

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC7330459/

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.

摘要

背景

需要更好的方法来确定维生素 A 吸收效率。

目的

我们的目的是通过改编先前用于测定胆固醇吸收的血浆同位素比方法来测量大鼠的维生素 A 吸收。

方法

雄性 Sprague-Dawley 大鼠 [n = 14；340 ± 16 g（平均值 ± 标准差）] 口服油中的 [3H]视黄基乙酸酯示踪剂剂量，并静脉注射在十二指肠内给予 [14C]视黄基乙酸酯的供体大鼠制备的 [14C]维生素 A 标记的乳糜。在第 1、2、3、6、9 和 12 天收集血样，并分析血浆中的 3H 和 14C；通过（口服剂量分数/静脉剂量分数）×100 计算每个样本的维生素 A 吸收。还测量了第 3、6、9 和 12 天收集的粪便和尿液池以及第 12 天的肝脏和剩余尸体中的放射性。

结果

以血浆同位素比计算的维生素 A 吸收在第 1 天>100%，第 6 天 78%±5%，第 9 天 76%±5%，第 12 天 74%±5%；拟合数据到指数函数加常数预测第 14 天吸收 75%。粪便中口服剂量的回收率较低（第 0 天至第 6 天为 6.2%±0.84%，n=10），第 9-12 天尿液池的平均同位素比低于血浆。