Summary
The current-voltage (I/V) technique was employed to investigate the different electrophysiological states of theChara plasmalemma and their interaction under a range of conditions. In K+ state the membrane became very permeable (conductances >20 S m 2) as [K+]0 increased to 10mm. As the cells were then easily damaged by the voltage-clamp procedures, it was difficult to determine the saturation K+ conductance. TEA (tetraethylammonium chloride) reversibly blocked the K+ channels, but had no effect on theI/V curve of the pump state, indicating that the K+ channels were not participating in this state. Acid pH0 (4.5) diminished the K+ conductance, but did not alter the response of the K+ channels to change in [K+]0. Alkaline pH0 (11.0) madeChara resting PD “bistable”: the PD either stayed near the estimatedE K and theI/V curve showed a negative conductance region typical of the K+ state, or it hyperpolarized and the near-linearI/V profile of the proton-permeable state was observed.
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Beilby, M.J. Potassium channels and different states ofChara plasmalemma. J. Membrain Biol. 89, 241–249 (1986). https://doi.org/10.1007/BF01870667
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DOI: https://doi.org/10.1007/BF01870667