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Plant Physiology 65:1-5 (1980) © 1980 American Society of Plant Biologists Membrane Potentials of Vallisneria Leaf Cells and Their Relation to Photosynthesis 1Department of Botany, Washington State University, Pullman, Washington 99164
A study has been made of the effects of the inhibitors carbonylcyanide m-chlorophenylhydrazone (CCCP), 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU), and of anoxia on the light-sensitive membrane potential of Vallisneria leaf cells. The present results are compared with the known effects of these inhibitors on ion transport and photosynthesis (Prins 1974 Ph.D thesis). The membrane potential is composed of a diffusion potential plus an electrogenic component. The electrogenic potential is about 13 millivolts in the dark and 80 millivolts in the light. The inhibitory effect of DCMU and CCCP on the electrogenic mechanisms strongly depends on the light intensity used, the inhibition being less at a higher light intensity. This is of significance in view of the often conflicting results obtained with these inhibitors. With ion transport in Vallisneria the electrogenic pump derives its energy from phosphorylation; however, the process which causes the initial light-induced hyperpolarization and the process that keeps the membrane potential at a steady hyperpolarized state in the light have different energy requirements. The action of photosystem I alone is sufficient to induce the initial hyperpolarization. For continuous operation in the light the activity of photosystem II also is needed.
2 To whom requests for reprints should be addressed. Permanent address: Department of Plant Physiology, Biological Centre, University of Groningen, P. O. Box 14, 9750 AA Haren, The Netherlands. 3 Present address: Agronomy Department, University of Wisconsin, Madison, Wisconsin 53706. 4 Present address: University of Washington, Friday Harbor Laboratories, Friday Harbor, Washington 98250. 1 This research was supported by a grant from the Dutch Organization for the Advancement of Pure Research (Z.W.O.) to H. B. A. Prins for his stay at Washington State University. This article has been cited by other articles:
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