代谢
铜主要通过消化道吸收，但也可以通过吸入和皮肤吸收。它通过基底外侧膜，可能是通过调节铜转运蛋白，并与血清白蛋白结合被运输到肝脏和肾脏。肝脏是铜稳态的关键器官。在肝脏和其他组织中，铜以与金属硫蛋白、氨基酸以及与依赖铜的酶相关联的形式储存，然后分配通过胆汁排泄或并入细胞内和细胞外蛋白中。铜通过血浆中与血清白蛋白、铜蓝蛋白或低分子量复合物结合被运输到外周组织。铜可能诱导金属硫蛋白和铜蓝蛋白的产生。膜结合的铜转运三磷酸腺苷酶（Cu-ATPase）将铜离子输送到细胞内和细胞外。生理上正常的铜水平通过改变铜的吸收速率和量、分布区域以及排泄来维持恒定。摄入一定量的硝酸盐和亚硝酸盐是人类氮循环的正常部分。在适当的条件下，硝酸盐可以在消化道内转化为亚硝酸盐，显著增强硝酸盐的毒性。硝酸盐的主要代谢途径是转化为亚硝酸盐，然后转化为氨。亚硝酸盐、硝酸盐及其代谢物通过尿液排出体外。
Copper is mainly absorbed through the gastrointestinal tract, but it can also be inhalated and absorbed dermally. It passes through the basolateral membrane, possibly via regulatory copper transporters, and is transported to the liver and kidney bound to serum albumin. The liver is the critical organ for copper homoeostasis. In the liver and other tissues, copper is stored bound to metallothionein, amino acids, and in association with copper-dependent enzymes, then partitioned for excretion through the bile or incorporation into intra- and extracellular proteins. The transport of copper to the peripheral tissues is accomplished through the plasma attached to serum albumin, ceruloplasmin or low-molecular-weight complexes. Copper may induce the production of metallothionein and ceruloplasmin. The membrane-bound copper transporting adenosine triphosphatase (Cu-ATPase) transports copper ions into and out of cells. Physiologically normal levels of copper in the body are held constant by alterations in the rate and amount of copper absorption, compartmental distribution, and excretion. Intake of some amount of nitrates and nitrites is a normal part of the nitrogen cycle in humans. In vivo conversion of nitrates to nitrites can occur in the gastrointestional tract under the right conditions, significantly enhancing nitrates' toxic potency. The major metabolic pathway for nitrate is conversion to nitrite, and then to ammonia. Nitrites, nitrates, and their metabolites are excreted in the urine. (L1137, L277, L279)
来源:Toxin and Toxin Target Database (T3DB)
