Characterization of the Ca^ -Dependent Cl^- Efflux in Perfused Chara Cells : MEMBRANES AND BIOENERGETICS

元データ 日本植物生理学会

概要

The mechanism of the Ca^<2+>-dependent Cl^- efflux was studied in tonoplast-free cells, in which the intracellular chemical composition can be freely controlled. Tonoplast-free cells were prepared by perfusing the cell interior of internodal cells of Chara corallina with a medium that contained EGTA. The Ca^<2+>-induced Cl^- efflux was measured together with the membrane potential during continuous intracellular perfusion. The dependencies of Cl^- efflux and the membrane potential on the intracellular Ca^<2+> or Cl^- concentrations were analyzed. When perfusion was started with medium that contained Ca^<2+> ions, Cl^- efflux and membrane depolarization were induced. The amount of Cl^- efflux varied considerably among individual cells. The rate of efflux de-creased exponentially but a residual efflux remained detectable. The Cl^- efflux was induced at concentrations of Ca^<2+> ions above 1 μM and reached a maximum at 1 mM. By contrast, the membrane depolarization reached a maximum at about 10 μM Ca^<2+> . The rate of Cl^- efflux increased linearly with logarithmic increases in the intracellular Cl^- concentrations. These findings suggest that more than two kinds of Ca^<2+>-dependent Cl^- channel might be present in the plasma membrane. Addition of ATP or its removal from the perfusion medium did not affect the Ca^<2+>-dependent Cl^- efflux. Calmodulin antagonists slightly inhibited the Ca^<2+>-dependent Cl^- efflux.

著者

MIMURA Tetsuro Department of Biology, Graduate School of Science, Kobe University
Mimura Tetsuro Department Of Biological Science Faculty Of Science Nara-women's University
Mimura Tetsuro Department Of Life Science Faculty Of Science Himeji Institute Of Technology:(present)biological Lab
Shimmen Teruo Department of Life Science, Faculty of Science, Himeji Institute of Technology
Shimmen Teruo Department Of Biology Faculty Of Science University Of Tokyo
Shimmen Teruo Department Of Life Science Faculty Of Science Himeji Institute Of Technology
Shimmen Teruo Department Of Biology Faculty Of Science Osaka University:(present)department Of Botany Faculty Of S

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