Tanumihardjo S A
Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53706-1571, USA.
J Nutr. 2000 Nov;130(11):2844-9. doi: 10.1093/jn/130.11.2844.
Vitamin A assessment methods that indirectly determine liver reserves are still in development. The deuterated vitamin A assay has been successfully applied in several population groups, but large doses of vitamin A must be used and the gas chromatography/mass spectrometry analysis is not very sensitive. Therefore, 10,11,14,15-(13)C(4)-retinyl acetate was synthesized using a modified Wittig-Horner procedure. Thereafter, female Sprague-Dawley rats (n = 47) were fed a vitamin A-deficient diet and divided into three groups: low (L), moderate (M) and high (H) vitamin A. Groups L, M and H were supplemented with 35, 70 and 350 nmol of unlabeled retinyl acetate/d for 17 d. On d 18, three rats from each group were killed to determine baseline (13)C levels. Serum was prepared, and livers were collected and stored at -70 degrees C until analyzed with HPLC and gas chromatography/combustion/isotope ratio mass spectrometry. The remaining rats were supplemented with 52 nmol of (13)C(4)-retinyl acetate. Rats were killed on d 1, 2, 4 and 10. The calculated and measured values of total body reserves (TBR) of vitamin A were within 7% of each other overall, and the relationship was linear (r = 0.98, P < 0.0001). The calculated mean TBR were 0.49 +/- 0.03, 0.82 +/- 0.007 and 3.72 +/- 0.40 micromol, and the measured mean TBR were 0.50 +/- 0.045, 0.69 +/- 0.10 and 3.6 +/- 0.29 micromol for groups L, M and H, respectively. In contrast, serum retinol concentrations did not show a difference among the dietary groups: 1.32 +/- 0.14, 1.35 +/- 0.17 and 1.28 +/- 0.15 micromol/L for groups L, M and H, respectively (P = 0.25). In conclusion, this method offers more sensitivity than traditional methods and may be applicable to human vitamin A status assessment when TBR estimations are desired.
间接测定肝脏储备的维生素A评估方法仍在研发中。氘代维生素A检测法已在多个群体中成功应用，但必须使用大剂量的维生素A，且气相色谱/质谱分析的灵敏度不高。因此，采用改良的维蒂希-霍纳法合成了10,11,14,15-(13)C(4)-视黄醇乙酸酯。此后，将雌性斯普拉格-道利大鼠（n = 47）喂食维生素A缺乏的饲料，并分为三组：低（L）、中（M）和高（H）维生素A组。L、M和H组分别补充35、70和350 nmol未标记的视黄醇乙酸酯/天，持续17天。在第18天，每组处死3只大鼠以测定基线(13)C水平。制备血清，收集肝脏并储存在-70℃，直至用高效液相色谱和气相色谱/燃烧/同位素比率质谱分析。其余大鼠补充52 nmol的(13)C(4)-视黄醇乙酸酯。在第1、2、4和10天处死大鼠。维生素A全身储备（TBR）的计算值和测量值总体上相差在7%以内，且关系呈线性（r = 0.98，P < 0.0001）。L、M和H组的计算平均TBR分别为0.49±0.03、0.82±0.007和3.72±0.40 μmol，测量平均TBR分别为0.50±0.045、0.69±0.10和3.6±0.29 μmol。相比之下，各饮食组的血清视黄醇浓度没有差异：L、M和H组分别为1.32±0.14、1.35±0.17和1.28±0.15 μmol/L（P = 0.25）。总之，该方法比传统方法更具灵敏度，当需要估计TBR时，可能适用于人体维生素A状态评估。
