Smith K T, Cousins R J
J Nutr. 1980 Feb;110(2):316-23. doi: 10.1093/jn/110.2.316.
Quantitative measurements of zinc absorption were made using the isolated, vascularly perfused rat intestine as a model. The perfused intestine retains the ability to discriminate between absorption processes for calciu, copper, iron and zinc. Measurements of zinc absorption by the perfused intestine, using atomic absorption spectrophotometry, indicated the presence of a zinc pool within intestinal mucosal cells. The zinc concentration in the lumen of the perfused intestine was directly related to the amount of zinc that appeared in the vascular perfusate. Intestines obtained from zinc-deficient animals exhibited an ability to process greater quantities of zinc which resulted in enhanced absorption. The maximal rate of zinc absorption was 229 nmoles per hour with intestines from rats fed adequate amounts of zinc and 627 nmoles per hour when a zinc-deficient diet was fed. Administration of zinc to rats before isolation and perfusion of the intestine resulted in greater intracellular retention of zinc taken up from the lumen and correspondingly lesser amounts (75 nmoles per hour) transferred to the vascular supply. These data provide quantitative evidence that the perfused intestine retains its ability to exercise homeostatic control over the zinc absorption process and that the intestinal cell is a major site of regulation.
以分离的、血管灌注的大鼠肠道为模型，对锌吸收进行了定量测量。灌注的肠道保留了区分钙、铜、铁和锌吸收过程的能力。使用原子吸收分光光度法对灌注肠道的锌吸收进行测量，结果表明肠道黏膜细胞内存在锌池。灌注肠道腔内的锌浓度与血管灌注液中出现的锌量直接相关。从缺锌动物获取的肠道表现出处理更多锌的能力，这导致吸收增强。喂食适量锌的大鼠的肠道，锌吸收的最大速率为每小时229纳摩尔，而喂食缺锌饮食时为每小时627纳摩尔。在分离和灌注肠道之前给大鼠补锌，会导致从肠腔摄取的锌在细胞内保留更多，相应地转移到血管供应的量较少（每小时75纳摩尔）。这些数据提供了定量证据，表明灌注的肠道保留了对锌吸收过程进行稳态控制的能力，并且肠道细胞是主要的调节部位。
