Department of Botany, University of Guelph, Guelph, Ontario NIG 2W1 Canada.
Plant Physiol. 1987 Sep;85(1):62-5. doi: 10.1104/pp.85.1.62.
Profiles of (109)Cd efflux from roots into three solutions were determined for young intact plants of Agrostis gigantea and maize. The solutions were (a) nutrient culture medium containing 3 micromolar Cd at room temperature, (b) ice-cold 5 millimolar CaCl(2), and (c) ice-cold 5 millimolar PbCl(2). Efflux profiles were clearly resolved into three easily discernible components having fast, medium, and slow exchange rates. These results were unexpected for the situation where some intracellular Cd was present both as extractable Cd-binding peptide and in electron-dense granules within the cytoplasm and the vacuoles. Adding a fourth compartment to the curve-fitting model produced a splitting of the fast exchanging component. Use of these efflux kinetics to estimate Cd fluxes through membranes was inappropriate. However, they were useful in determining optimal washing times for the removal of extracellular Cd. A 10 minute wash in ice-cold 5 millimolar CaCl(2) is recommended for this purpose for Agrostis and maize roots.
测定了大麦和玉米幼根将 109Cd 主动排出到三种溶液中的情况。这三种溶液分别是：(a) 室温下含有 3 微摩尔 Cd 的营养培养液；(b) 冰冷的 5 毫摩尔 CaCl2；(c) 冰冷的 5 毫摩尔 PbCl2。排出曲线明显分为三个易于分辨的组分，具有快速、中速和慢速交换率。对于细胞质和液泡中存在部分细胞内 Cd 作为可提取的 Cd 结合肽和电子致密颗粒的情况，这些结果出人意料。向曲线拟合模型中添加第四个隔室会导致快速交换组分的分裂。使用这些排出动力学来估计通过膜的 Cd 通量是不合适的。然而，它们在确定去除细胞外 Cd 的最佳洗涤时间方面很有用。建议为此目的在冰冷的 5 毫摩尔 CaCl2 中洗涤 10 分钟，适用于大麦和玉米根。
