Alexander J, Aaseth J
Department of Environmental Medicine, National Institute of Public Health, Oslo, Norway.
Analyst. 1995 Mar;120(3):931-3. doi: 10.1039/an9952000931.
The transport of [51Cr]chromate into human erythrocytes and isolated rat hepatocytes has been investigated. It was found that uptake in both cell types could be inhibited by the established anion carrier inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. The uptake was very fast, and in kinetic studies a very low Km was found for both cell types, indicating either a high affinity of chromate for the carrier, and/or, more probably, an efficient intracellular reduction and trapping of 51Cr. The transport capacity, however, was of the same magnitude as for physiological substrates, such as lactate and sulfate. The uptake was temperature dependent and the activation energy was of the same magnitude as that for the physiological substrates. The uptake could be partly inhibited by high levels (mmol l-1) of lactate, pyruvate or sulfate. The uptake rate was greatly increased at lower pH (6.0 versus 7.4) which could indicate transport of the HCrO4- form or an increased intracellular rate of CrVI reduction. The results showed efficient uptake of 51CrO4(2-) by erythrocytes and hepatocytes. They were consistent with a mechanism of uptake which involved the cell membrane anion-exchange carrier in the transport and trapping of 51Cr within the cell.
已对[51Cr]铬酸盐进入人红细胞和分离的大鼠肝细胞的转运进行了研究。发现两种细胞类型的摄取均可被既定的阴离子载体抑制剂4,4'-二异硫氰基芪-2,2'-二磺酸抑制。摄取非常迅速，并且在动力学研究中发现两种细胞类型的Km都非常低，这表明铬酸盐对载体具有高亲和力，和/或更可能是51Cr在细胞内有效还原和捕获。然而，转运能力与生理底物（如乳酸盐和硫酸盐）的转运能力大小相同。摄取依赖于温度，活化能与生理底物的活化能大小相同。高浓度（mmol l-1）的乳酸盐、丙酮酸盐或硫酸盐可部分抑制摄取。在较低pH值（6.0对7.4）下摄取速率大大增加，这可能表明HCrO4-形式的转运或细胞内CrVI还原速率增加。结果表明红细胞和肝细胞对51CrO4(2-)有高效摄取。它们与一种摄取机制一致，该机制涉及细胞膜阴离子交换载体在细胞内转运和捕获51Cr。
