Ferricyanide Changes the Transport Properties of Lamprothamnium Papulosum Plasmalemma
External perfusion of the charophyte Lamprothamnium papulosum with medium containing 0.5 mM ferricyanide induced depolarization of the transmembrane potential. The depolarization was associated with a decrease in membrane resistance, presumably due to an increase in K+ conductance.
During the depolarization cytoplasmic streaming slowed down transiently. The decrease of streaming velocity could be overcome by lowering the external Ca2+ concentration or preconditioning the cells with the Ca2+ channel blocker La3+. Since cytoplasmic streaming is sensitive to the concentration of cytoplasmic free Ca2+ it seems as if Fe3+Cy stimulates Ca2+ influx. As a sequence of events we propose: The transmembrane reduction is a depolarizing current. The depolarization triggers the opening of voltage gated Ca2+ and/or K+ channels.
However, the Fe3+Cy stimulated net proton efflux was not a result of the membrane depolarization.
KeywordsPermeability Maize EDTA Assure Hepes
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