Conrad M E, Barton J C
Gastroenterology. 1978 Apr;74(4):731-40.
A reliable method for studying lead absorption and excretion in rats is described. Lead absorption occurs primarily in theduodenum where lead enters the epithelial mucosal cells. There is a relative mucosal block for lead with increasing intraluminal doses. Certain substances which bind lead and increase its solubility enhance its absorption. Iron, zinc, and calcium decrease the absorption of lead without affecting its solubility, probably by competing for shared absorptive receptors in the intestinal mucosa. The total body burden of lead does not affect lead absorption. Thus, lead does not have a feedback mechanism which limits absorption. Lead absorption is increased during rapid periods of growth and in iron-deficient animals. It is diminished with starvation and in iron-overloaded animals. The excretion and kinetics of tracer doses of radiolead were quantified. Erythrocytes seem to serve an important role in transport. Excretion occurs in urine and stool. Bile is an important route of excretion in the gut. Although most of a tracer dose is rapidly excreted, the excretory process is limited permitting lead accumulation primarily in bone.
本文描述了一种研究大鼠铅吸收和排泄的可靠方法。铅的吸收主要发生在十二指肠，铅由此进入上皮黏膜细胞。随着肠腔内剂量的增加，铅存在相对的黏膜屏障。某些能结合铅并增加其溶解度的物质会增强铅的吸收。铁、锌和钙可降低铅的吸收，但不影响其溶解度，这可能是通过竞争肠黏膜中共享的吸收受体来实现的。铅的全身负荷并不影响铅的吸收。因此，铅没有限制吸收的反馈机制。在快速生长阶段以及缺铁动物中，铅的吸收会增加。而在饥饿状态和铁过载动物中，铅的吸收会减少。对微量放射性铅的排泄和动力学进行了量化。红细胞似乎在运输过程中发挥着重要作用。铅通过尿液和粪便排出。胆汁是肠道内重要的排泄途径。尽管大部分微量剂量的铅会迅速排出，但排泄过程有限，这使得铅主要在骨骼中蓄积。
