Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4K1.
Comp Biochem Physiol C Toxicol Pharmacol. 2013 Mar;157(2):236-50. doi: 10.1016/j.cbpc.2012.11.006. Epub 2012 Nov 29.
Transport of calcium (Ca) and cadmium (Cd) was examined along the gastro-intestinal tract (GIT) of freshwater and seawater Oncorhynchus mykiss irideus (FWT and SWTies respectively) using in vitro and in vivo experiments. Based on known physiological differences between FWT and SWT which aid in regulating ion levels and osmolarity, we hypothesized that SWT would have lower rates of Ca uptake. Also, we predicted that Cd rates would also be lower because Cd is known to share a common transport mechanism with Ca. Kinetics of Ca and Cd transport were determined using mucosal salines of varying concentrations [1, 10, 30, 60, and 100 (mmolL(-1) for Ca, μmolL(-1) for Cd)]. Linear and saturating relationships were found for Ca for FWT and SWT, but overall SWT had lower rates. Linear and/or saturating relationships were also found for Cd uptake, but rates varied little between fish types. Elevated Ca had no inhibitory effect on Cd transport, and Ca channel blockers nifedipine and verapamil had little effect on Ca or Cd uptake. However, lanthanum reduced Ca transport into some compartments. A 21 day in vivo feeding experiment was also performed where FWT and SWT were exposed to control diets or Cd-spiked diets (552 μg Cd g(-1) food). Whole body Cd uptake between fish types was similar, but the majority of Cd in SWT remained in the posterior intestine tissue, while FWT transported more Cd through their gut wall. Overall it appears that large differences in Ca and Cd uptake between FWT and SWT exist, with SWT generally having lower rates.
采用体内和体外实验，研究了淡水和海水虹鳟鱼（分别为 FWT 和 SWT）沿胃肠道（GIT）的钙（Ca）和镉（Cd）转运。基于 FWT 和 SWT 之间已知的有助于调节离子水平和渗透压的生理差异，我们假设 SWT 的 Ca 摄取率较低。此外，我们预测 Cd 摄取率也会较低，因为 Cd 已知与 Ca 共享共同的转运机制。使用不同浓度的粘膜生理盐水 [1、10、30、60 和 100（mmolL（-1）用于 Ca，μmolL（-1）用于 Cd）] 确定 Ca 和 Cd 转运的动力学。对于 FWT 和 SWT，发现 Ca 具有线性和饱和关系，但总体而言 SWT 的速率较低。对于 Cd 摄取也发现了线性和/或饱和关系，但鱼类类型之间的速率变化很小。升高的 Ca 对 Cd 转运没有抑制作用，Ca 通道阻滞剂硝苯地平和维拉帕米对 Ca 或 Cd 摄取的影响很小。然而，镧减少了 Ca 向某些隔室的转运。还进行了为期 21 天的体内喂养实验，其中 FWT 和 SWT 暴露于对照饮食或 Cd 污染饮食（552 μg Cd g（-1）食物）。鱼类类型之间的全身 Cd 摄取相似，但 SWT 中的大部分 Cd 仍留在后肠组织中，而 FWT 通过肠壁转运更多的 Cd。总体而言，FWT 和 SWT 之间的 Ca 和 Cd 摄取存在很大差异，SWT 的摄取率通常较低。
