Bevan C, Foulkes E C
Department of Environmental Health, University of Cincinnati, College of Medicine, OH 45267-0056.
Toxicology. 1989 Mar;54(3):297-309. doi: 10.1016/0300-483x(89)90065-6.
Cd2+ uptake by brush border membrane vesicles isolated from rat small intestine was investigated by a rapid filtration technique. Cd2+ uptake showed time- and temperature-dependence. Changes in medium osmolarity had no effect on Cd2+ uptake, indicating that the process involves primarily binding of Cd2+ to membrane component(s). Membrane-impermeable chelating agents removed only about 60-65% of the bound cadmium from intact vesicles preincubated with Cd; almost all Cd was removed by chelators when membrane permeability was increased by 1-butanol. Thus Cd uptake by membrane vesicles results in binding to both sides of the membrane. Pretreatment of vesicles with cadmium resulted in a time-dependent inhibition of D-glucose uptake in the presence of a sodium (but no potassium) gradient. This inhibition is correlated with Cd binding to external sites on the D-glucose transporter, and not the driving force for D-glucose transport.
采用快速过滤技术研究了从大鼠小肠分离的刷状缘膜囊泡对Cd2+的摄取。Cd2+摄取表现出时间和温度依赖性。培养基渗透压的变化对Cd2+摄取没有影响，表明该过程主要涉及Cd2+与膜成分的结合。膜不可渗透的螯合剂仅从预先用Cd孵育的完整囊泡中去除约60-65%的结合镉；当用1-丁醇增加膜通透性时，几乎所有的Cd都被螯合剂去除。因此，膜囊泡对Cd的摄取导致其与膜的两侧结合。在存在钠（但无钾）梯度的情况下，用镉预处理囊泡会导致D-葡萄糖摄取随时间依赖性抑制。这种抑制与Cd结合到D-葡萄糖转运蛋白的外部位点有关，而不是与D-葡萄糖转运的驱动力有关。
