Department of Biophysical Engineering, Faculty of Engineering Science, Osaka University, 560, Toyonaka, Japan.
Planta. 1980 Aug;149(3):213-8. doi: 10.1007/BF00384556.
The dependence of the membrane potential (Em) and the membrane resistance (Rm) of Chara australis R. Brown on the pH of the external medium (pH0) was studied by controlling the activity of the plasmamembrane H(+) pump under both light and dark conditions. The activity of the pump was controlled by regulating the internal ATP or Mg(2+) concentration in tonoplast-free cells prepared by vacuolar perfusion. In these cells, which contained Mg · ATP (mgATP cells), Em and Rm were very sensitive to pH0, as in normal cells. Em was more negative in light than in the dark at all pH0 values tested. Tonoplast-free cells with very low [ATP]i (-ATP cells) or [Mg(2+)]i (-Mg cells) showed very weak dependence of Em and Rm on pH0. Thus, the active and not the passive component of Em was sensitive to pH0. At the same time, the high permeability of the plasma membrane to H(+) was questioned. In both-ATP cells and-Mg cells, Em was scarcely affected and Rm markedly decreased on illumination.
研究了 Chara australis R. Brown 的膜电位 (Em) 和膜电阻 (Rm) 对外部介质 pH 值 (pH0) 的依赖性，方法是在光照和黑暗条件下控制质膜 H(+)泵的活性。通过调节无液泡灌注制备的无液泡细胞的内膜 ATP 或 Mg(2+) 浓度来控制泵的活性。在这些含有 Mg·ATP (mgATP 细胞) 的细胞中，Em 和 Rm 对 pH0 非常敏感，与正常细胞相同。在所有测试的 pH0 值下，Em 在光照下比在黑暗中更负。具有非常低的 [ATP]i (-ATP 细胞) 或 [Mg(2+)]i (-Mg 细胞) 的无液泡细胞对 pH0 的依赖性非常弱。因此，Em 的主动而非被动成分对 pH0 敏感。同时，质疑了质膜对 H(+) 的高通透性。在-ATP 细胞和-Mg 细胞中，Em 几乎不受影响，而 Rm 在光照下明显下降。
