Relationship between light-induced potential change and internal ATP concentration in tonoplast-free Chara cells :

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    • Kikuyama Munehiro
    • Department of Biology, Faculty of Science, Osaka University:(Present)Niigata College of Pharmacy
    • Hayama Tomio
    • Department of Biology, Faculty of Science, Osaka University
    • Fujii Sumiko
    • Department of Biology, Faculty of Science, Osaka University:(Present)Department of Agricultural Chemistry, College of Agriculture. Kyoto University
    • Tazawa Masashi
    • Department of Biology, Faculty of Science, Osaka University:(Present)Department of Botany. Faculty of Science. University of Tokyo


The effect of the intracellular concentration of ATP ([ATP]_i) on the light-induced potential change (LPC) in tonoplast-free Chara cells was studied. The LPC was hardly affected by lowering the [ATP]_i by about 1/10 or by raising it to about 10 times the normal cytoplasmic concentration (0.5-1.3 m_M). The insensitivity of LPC to [ATP]_i excludes the possibility that an increase in [ATP]_i due to photosynthesis may induce the LPC. However, extreme lowering of the [ATP]_i to about 1-2 μ_M completely inhibited LPC, although photosynthetic O_2 evolution was not significantly inhibited. This fact supports the hypothesis that light stimulates the putative H^+-pump fueled by ATP. The uncoupling agents DNP and CCCP greatly depolarized the membrane, and inhibited LPC strongly, but they did not decrease [ATP]_i. Photosynthetic O_2 evolution was inhibited to some extent by 2 μ_M CCCP and strongly inhibited by 0.1 m_M DNP. Since the membrane resistance increased significantly, these chemicals are believed to act on the membrane as an inhibitor of the electrogenic H^+ pump not as an H^+ conductor. Introduction of 1 m_M ATP into cells treated with uncouplers, to a large extent restored their ability to produce LPC although the membrane potential in darkness was maintained at a low level.


  • Plant and cell physiology

    Plant and cell physiology 20(6), 993-1002, 1979

    Japanese Society of Plant Physiologists

Cited by:  3


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