Some characteristics of membrane Cd2+ transport in rat thymocytes: an analysis using Fluo-3
| Autor: | Masahiro Fujinaga, Yasuo Oyama, Isao Kurotani, Masaya Satoh, Shoji Imai, Erika Hashimoto, Kazuki Koizumi, Takuya Kawanai, Norikazu Miyoshi |
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| Rok vydání: | 2011 |
| Předmět: |
Membrane potential
Fluo-3 Antiporter Metals and Alloys Membrane transport General Biochemistry Genetics and Molecular Biology Biomaterials chemistry.chemical_compound Membrane chemistry Biochemistry Biophysics Plasma membrane Ca2+ ATPase General Agricultural and Biological Sciences Electrochemical gradient Intracellular |
| Zdroj: | BioMetals. 24:903-914 |
| ISSN: | 1572-8773 0966-0844 |
| Popis: | Although cadmium-induced apoptosis of lymphocytes is one of common features in the immunotoxicity of cadmium, the membrane pathway for intracellular cadmium accumulation is not fully elucidated. To characterize membrane Cd2+ transport of rat thymocytes, the change in intracellular Cd2+ concentration under various conditions was examined by the use of Fluo-3, a fluorescent probe for monitoring the change in intracellular concentration of divalent metal cations. The membrane Cd2+ transport was estimated by the augmentation of Fluo-3 fluorescence induced by bath application of CdCl2. Lowering temperature strongly suppressed the augmentation of Fluo-3 fluorescence by CdCl2, suggesting that the metabolic process can be involved in membrane Cd2+ transport. External acidification (decreasing pH) and membrane depolarization by adding KCl attenuated the augmentation, indicating the requirement of electrochemical driving force for membrane Cd2+ transport into the cells. Bath application of CaCl2 and ZnCl2 equally decreased the augmentation, suggesting their competition with Cd2+ at the membrane transport. The augmentation by CdCl2 was lesser in the cells treated with N-ethylmaleimide inducing chemical depletion of cellular thiols. The result suggests the contribution of sulfhydryl groups to membrane Cd2+ transport. Taken together, it is suggested that the cells possess a temperature-sensitive membrane Cd2+ pathway, driven by electrochemical gradient of Cd2+ and transmembrane potential, with competitive binding site. Based on the characteristics described above, it is unlikely that the membrane Cd2+ transport in rat thymocytes is attributed to a single transport system although it has characteristics that are similar to those of divalent cation transporter 1. |
| Databáze: | OpenAIRE |
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