H+ tolerance of Chara Internodal Cells and Apparent Net Influx of H+ in Weakly Acidic Solutions: Implication of the Net Flux of H+ as a Minor Component among the Total Net Flux of Ions across the Intact Cell Membrane of Chara |
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Authors: | Kiyosawa Keitaro |
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Institution: | Department of Biophysical Engineering, Faculty of Engineering Science, Osaka University Toyonaka, Osaka, 560 Japan |
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Abstract: | Precise measurements of the net flux of protons in Chara internodalcells were made with a recently designed high-resolution pH-meter.Survival of intact Chara internodal cells in artificial pondwater (APW) that contained HC1 at various concentrations wasalso examined. The apparent net flux of H+ was inward and muchsmaller than that reported so far. In APW at pH 4.005, a valuehigher than the extracellular pH expected from the values ofH+ efflux reported to date, all of the intact Chara internodalcells died within a day. With reference to the data on the circadianflow of ions in the pulvinus of Phaseolus Kiyosawa (1979) PlantCell Physiol. 20: 16211634, Hosokawa and Kiyosawa (1983)Plant Cell Physiol. 24: 10651072] and ionic regulationin Chara L-cells Kiyosawa and Okihara (1988) Plant Cell Physiol.29: 919], a discussion is presented of the prossiblyminor contribution of the net flux of H+ in the generation ofthe electrical membrane potential. Regulation of the net fluxof H+ in weakly acidic APW is also discussed. (Received September 4, 1989; Accepted January 25, 1990) |
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