Boza J J, Fox T E, Eagles J, Wilson P D, Fairweather-Tait S J
Department of Nutrition Diet and Health, Norwich Laboratory, Norwich Research Park, United Kingdom.
J Nutr. 1995 Jun;125(6):1611-6. doi: 10.1093/jn/125.6.1611.
The use of extrinsic stable and radioisotopic labels (Fe, Zn, Cu and Se) was compared with the use of intrinsic labels by measuring label retention in rats. Saccharomyces cerevisiae (Hansen strain CBS 1171) was prepared intrinsically enriched with a stable isotope of iron, zinc, copper or selenium, and unenriched freeze-dried yeast was extrinsically labeled with the appropriate stable and/or radioisotope. Male Wistar rats, weighing 80-100 g and fed a purified diet, were given a test meal of one of the above labeled yeasts. Isotopic retention was determined by fecal monitoring. Retention of the stable isotopes was determined by thermal ionization quadruple mass spectrometry (TIQMS) and retention of the radioisotopes by counting feces in a whole-body counter. The results indicated that the behavior of the labels differed among the minerals, with copper as the only one in which the intrinsic and extrinsic stable isotopes were comparably retained. With zinc, retention of the extrinsic radiolabel and intrinsic label was similar, but retention of the extrinsic stable isotope label was higher. With iron, the intrinsic label had a significantly lower retention than the two extrinsic labels; with selenium, retention of all three labels was different, but these differences were not of a sufficient magnitude to conclude that extrinsic stable isotopic labelling is not valid. These results demonstrate that an extrinsic stable isotope label can be used for copper, selenium and inorganic iron, but that such a label is not valid for studies on zinc.
通过测量大鼠体内的标记物保留情况，比较了外在稳定同位素标记物（铁、锌、铜和硒）与内在标记物的使用效果。酿酒酵母（汉森菌株CBS 1171）被制备成内在富含铁、锌、铜或硒的稳定同位素，未富集的冻干酵母则用适当的稳定同位素和/或放射性同位素进行外在标记。体重80 - 100克且喂食纯化饮食的雄性Wistar大鼠，被给予上述标记酵母之一作为测试餐。通过粪便监测来确定同位素保留情况。稳定同位素的保留情况通过热电离四极质谱法（TIQMS）测定，放射性同位素的保留情况通过在全身计数器中对粪便进行计数来测定。结果表明，不同矿物质的标记物行为有所不同，铜是唯一内在和外在稳定同位素保留情况相当的矿物质。对于锌，外在放射性标记物和内在标记物的保留情况相似，但外在稳定同位素标记物的保留率更高。对于铁，内在标记物的保留率显著低于两种外在标记物；对于硒，三种标记物的保留情况都不同，但这些差异的幅度不足以得出外在稳定同位素标记无效的结论。这些结果表明，外在稳定同位素标记物可用于铜、硒和无机铁的研究，但这种标记物不适用于锌的研究。
