Schaeffer M C, Sampson D A, Skala J H, O'Connor D K, Gretz D
U.S. Department of Agriculture, Western Human Nutrition Research Center, San Francisco, CA 94129.
J Nutr. 1991 Oct;121(10):1627-34. doi: 10.1093/jn/121.10.1627.
The tryptophan-load test for vitamin B-6 nutritional status was administered to adult female Long-Evans rats fed graded levels of pyridoxine hydrochloride (PN.HCl) in two experiments, and its sensitivity to marginal vitamin B-6 intake was evaluated. In Experiment 1, rats were 4-h meal-fed an AIN-76A (20% casein) diet devoid of PN.HCl for 3 wk, then repleted (n = 12) for 6 wk with 4-h pair-fed meals of either 0.25, 0.5, 1.0 or 7.0 (control) mg PN.HCl/kg diet. In Experiment 2, rats (n = 16) were pair-fed for 10 wk either 0.0, 0.5, 1.0 or 7.0 (control) mg PN.HCl/kg diet, with 24-h access to food. Vitamin B-6 nutritional status was assessed at the end of each experiment. Except in rats fed 0 mg PN.HCl/kg diet, mean body weights were not significantly different among diet groups of either experiment. Plasma pyridoxal phosphate (PLP), pyridoxal and total vitamin B-6 concentrations, determined by HPLC, were very sensitive to gradations in dietary PN.HCl concentrations (P less than 0.05). Red blood cell endogenous and PLP-stimulated alanine and aspartate aminotransferase activity did not statistically differentiate all levels of dietary vitamin B-6, although the calculated activity coefficient for each enzyme (stimulated/endogenous activity) did. Urinary xanthurenic acid excretion following a tryptophan load [24.5 mumol (5 mg) L-tryptophan/100 g body weight, injected intraperitoneally] was significantly (P less than 0.05) elevated compared with controls only in the group fed 0 mg PN/HCl/kg diet. At the tryptophan dose used here, the tryptophan-load test was not useful in detecting marginal vitamin B-6 intake in rats.
在两项实验中，对喂食不同水平盐酸吡哆醇（PN.HCl）的成年雌性Long-Evans大鼠进行了色氨酸负荷试验，以评估其维生素B-6营养状况，并评估该试验对边缘性维生素B-6摄入量的敏感性。在实验1中，大鼠连续3周4小时进食不含PN.HCl的AIN-76A（20%酪蛋白）日粮，然后用每千克日粮含0.25、0.5、1.0或7.0（对照）毫克PN.HCl的4小时配对喂食日粮再补充6周（n = 12）。在实验2中，大鼠（n = 16）连续10周配对喂食每千克日粮含0.0、0.5、1.0或7.0（对照）毫克PN.HCl的日粮，可24小时进食。在每个实验结束时评估维生素B-6营养状况。除了喂食每千克日粮含0毫克PN.HCl的大鼠外，两个实验中各日粮组的平均体重没有显著差异。通过高效液相色谱法测定的血浆磷酸吡哆醛（PLP）、吡哆醛和总维生素B-6浓度对日粮中PN.HCl浓度的梯度变化非常敏感（P < 0.05）。红细胞内源性和PLP刺激的丙氨酸和天冬氨酸转氨酶活性虽然各酶的计算活性系数（刺激/内源性活性）能区分，但在统计学上不能区分所有日粮维生素B-6水平。色氨酸负荷后（腹腔注射24.5微摩尔（5毫克）L-色氨酸/100克体重）的尿黄尿酸排泄量仅在喂食每千克日粮含0毫克PN/HCl的组中与对照组相比显著升高（P < 0.05）。在此处使用的色氨酸剂量下，色氨酸负荷试验在检测大鼠边缘性维生素B-6摄入量方面没有用处。
