Tallkvist J, Tjälve H
Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, Uppsala Biomedical Centre.
Pharmacol Toxicol. 1994 Nov;75(5):233-43. doi: 10.1111/j.1600-0773.1994.tb00354.x.
The intestinal absorption of Ni2+ was studied in isolated perfused jejunal and ileal segments of rats, by a method which allows continuous sampling of the absorbates. The results showed that the Ni(2+)-absorption proceeds at a much higher rate in the jejunum than in the ileum. Several observations indicate that Ni2+ is absorbed actively in the jejunum. There are indications in the literature that Ni2+ at least partly may share the transport mechanism for iron across the intestinal mucosa and our results may reflect the participation of Ni2+ in this absorptive process. The transfer of Ni2+ across the ileal epithelium may occur by passive diffusion. Addition of Zn2+, Co2+, Cd2+ or Hg2+ to the jejunal perfusates affected the Ni(2+)-absorption to varying extents. Thus, Zn2+ had minor effects on the Ni(2+)-absorption. Co2+ decreased the Ni(2+)-concentration in the absorbates, possibly by interfering with Ni2+ in the iron transfer process. Addition of Cd2+ or Hg2+ to the perfusates resulted in decreased jejunal water absorption. Hg2+ also depressed the glucose absorption. These results show that Cd2+ and Hg2+ at low concentrations are toxic to the jejunal mucosal cells. Thus, these metals can inhibit the amount of Ni2+ transferred across the intestinal mucosa by decreasing the volume of the absorbate.
采用一种可对吸收液进行连续取样的方法，对大鼠离体灌注空肠段和回肠段中Ni2+的肠道吸收进行了研究。结果表明，Ni(2+)在空肠中的吸收速率比在回肠中高得多。多项观察表明，Ni2+在空肠中是主动吸收的。文献中有迹象表明，Ni2+至少部分可能与铁跨肠黏膜的转运机制相同，我们的结果可能反映了Ni2+参与了这一吸收过程。Ni2+跨回肠上皮的转运可能通过被动扩散发生。向空肠灌注液中添加Zn2+、Co2+、Cd2+或Hg2+会在不同程度上影响Ni(2+)的吸收。因此，Zn2+对Ni(2+)的吸收影响较小。Co2+降低了吸收液中Ni(2+)的浓度，可能是通过干扰铁转运过程中的Ni2+。向灌注液中添加Cd2+或Hg2+会导致空肠水吸收减少。Hg2+还抑制了葡萄糖吸收。这些结果表明，低浓度的Cd2+和Hg2+对空肠黏膜细胞有毒性。因此，这些金属可通过减少吸收液的体积来抑制跨肠黏膜转运的Ni2+量。
