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

元データ 日本植物生理学会

概要

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.

著者

Kikuyama M Niigata Univ. Niigata Jpn
Tazawa M Fukui Univ. Technol. Fukui Jpn
Tazawa Masashi Department Of Applied Physics And Chemistry Fukui University Of Technology
Tazawa Masashi Department Of Biology Faculty Of Science Osaka University:(present)department Of Botany Faculty Of S
Hayama Tomio Faculty of Medicine, Kumamoto University
Kikuyama Munehiro Department of Biology, Faculty of Science, Osaka University
Hayama Tomio Department of Biology, Faculty of Science, Osaka University
Fujii Sumiko Department of Biology, Faculty of Science, Osaka University
Hayama Tomio Faculty Of Medicine Kumamoto University
Fujii Sumiko Department Of Biology Faculty Of Science Osaka University
Kikuyama Munehiro Biological Laboratory The University Of The Air.
Kikuyama Munehiro Department Of Biology Faculty Of Science Niigata University
Tazawa Masashi Departlnent Of Biology Faculty Of Science Osaka University

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