Duncan T E, Green J B, Green M H
Nutrition Department, Pennsylvania State University, University Park 16802.
J Nutr. 1993 May;123(5):933-9. doi: 10.1093/jn/123.5.933.
We tested the hypothesis that the fraction of an injected dose (FDp) of [3H]retinol remaining in plasma could be used to predict liver vitamin A mass. Rats (n = 36) with liver vitamin A ranging from 1.4 to 23,000 nmol received an intravenous dose of [3H]retinol-labeled plasma. Plasma samples obtained at 4, 4.4, 5, 5.4, 6, 7 and 8 d were analyzed for radioactivity; liver vitamin A levels were determined at 8 d. Using a regression equation developed previously [liver vitamin A (nmol) = 7493.exp(-148.FDp)], there was a log linear relationship between FDp and liver vitamin A mass from 1.4 to 5200 nmol retinol; the equation did not predict levels > or = 7500 nmol. By expanding the regression equation [liver vitamin A (nmol) = 88,928.exp(-1347.FDp) + 5606.exp(-120.FDp)] and using the FDp at 4.4 d, liver vitamin A levels ranging from < 4 to 23,000 nmol were well predicted. Satisfactory equations were also developed for data obtained at 4, 5 and 5.4 d. We conclude that this modified isotope dilution technique is a sensitive and reliable method for assessing vitamin A status in rats over a wide range of vitamin A nutriture. It is likely that this method could be modified for use in humans.
血浆中剩余的[3H]视黄醇注射剂量分数（FDp）可用于预测肝脏维生素A含量。肝脏维生素A含量在1.4至23,000 nmol之间的大鼠（n = 36）接受静脉注射[3H]视黄醇标记的血浆。在第4、4.4、5、5.4、6、7和8天采集血浆样本并分析放射性；在第8天测定肝脏维生素A水平。使用先前建立的回归方程[肝脏维生素A（nmol）= 7493.exp（-148.FDp）]，FDp与1.4至5200 nmol视黄醇的肝脏维生素A含量之间存在对数线性关系；该方程无法预测≥7500 nmol的水平。通过扩展回归方程[肝脏维生素A（nmol）= 88,928.exp（-1347.FDp）+ 5606.exp（-120.FDp）]并使用4.4天时的FDp，可以很好地预测<4至23,000 nmol的肝脏维生素A水平。还针对在第4、5和5.4天获得的数据建立了令人满意的方程。我们得出结论，这种改良的同位素稀释技术是一种在广泛的维生素A营养范围内评估大鼠维生素A状态的灵敏且可靠的方法。很可能这种方法可以进行改良以用于人类。
