Hoadley J E, Cousins R J
Proc Soc Exp Biol Med. 1985 Nov;180(2):296-302. doi: 10.3181/00379727-180-42179.
The effects of Zn depletion and short-term fasting on intestinal transport of Cd were examined in perfused rat small intestines. The small intestine was isolated with its vascular network intact, then simultaneously perfused from the luminal and vascular sides. A Zn-depleted state that results in marked hypozincemia was produced in some rats by feeding a Zn-deficient diet for 4 days. Uptake of Cd from the luminal perfusate was greater in the Zn-depleted rats, whereas transport of Cd to the vascular perfusate was not affected. Fasting overnight prior to perfusion did not influence Cd transport nor alter the effect of Zn depletion on Cd uptake. The Cd concentration in the soluble fraction of intestinal mucosa from perfused intestines was not different between Zn-depleted and Zn-adequate rats. Gel filtration chromatography of the soluble fraction showed a shift in the distribution of Cd from metallothionein to high molecular weight ligands in intestines from Zn-depleted rats. The decrease in amount of metallothionein-associated Cd corresponded to a decrease of total intestinal metallothionein as measured by the Cd-binding assay. The results suggest association of Cd with intestinal metallothionein did not influence the absorption of Cd under these conditions.
在灌注的大鼠小肠中研究了锌缺乏和短期禁食对镉肠道转运的影响。小肠在其血管网络完整的情况下被分离出来，然后同时从肠腔侧和血管侧进行灌注。通过给一些大鼠喂食缺锌饮食4天，使其产生导致明显低锌血症的锌缺乏状态。锌缺乏的大鼠从肠腔灌注液中摄取镉的量更大，而镉向血管灌注液的转运不受影响。灌注前禁食过夜既不影响镉的转运，也不改变锌缺乏对镉摄取的影响。在灌注肠的肠黏膜可溶部分中，锌缺乏和锌充足的大鼠之间镉浓度没有差异。对可溶部分进行凝胶过滤色谱分析表明，在锌缺乏大鼠的肠道中，镉的分布从金属硫蛋白转移到了高分子量配体。通过镉结合试验测定，与金属硫蛋白结合的镉量减少与肠总金属硫蛋白的减少相对应。结果表明，在这些条件下，镉与肠金属硫蛋白的结合并不影响镉的吸收。
