Jacob T J, Duncan G
Exp Eye Res. 1983 Apr;36(4):595-605. doi: 10.1016/0014-4835(83)90053-2.
The effects of a range of divalent ions on lens sodium and potassium permeability characteristics were studied in calcium competition and replacement experiments. Resting voltage and conductance were measured and also voltage-independent conductance. Strontium and manganese were the only divalent ions able to maintain, in the absence of calcium, both sodium and potassium permeability at or near the control level. Neither cobalt nor magnesium had any effect on lens voltage of conductance in the presence of calcium, but neither of these ions could maintain lens permeability properties in the absence of calcium. Cadmium and barium had little effect on sodium permeability, but the former increased potassium permeability while the latter reduced it. Barium was the only divalent studied that appeared to inactivate voltage-sensitive potassium channels in the presence of calcium. Nickel, zinc and copper increased both sodium and potassium permeability in the presence of calcium and so they are likely to be particularly damaging to the lens. Copper was extremely toxic since it was able to overturn the regulatory influence of calcium when it was present in concentrations as low as 10(-6)M.
在钙竞争和替代实验中，研究了一系列二价离子对晶状体钠和钾通透性特征的影响。测量了静息电压、电导以及电压非依赖性电导。锶和锰是仅有的在无钙情况下能将钠和钾通透性维持在或接近对照水平的二价离子。在有钙存在时，钴和镁对晶状体电导电压均无影响，但在无钙情况下，这两种离子都不能维持晶状体的通透性特性。镉和钡对钠通透性影响不大，但前者增加钾通透性，而后者降低钾通透性。钡是所研究的唯一在有钙存在时似乎能使电压敏感性钾通道失活的二价离子。镍、锌和铜在有钙存在时增加钠和钾的通透性，因此它们可能对晶状体特别有害。铜极具毒性，因为当它以低至10(-6)M的浓度存在时就能颠覆钙的调节作用。
