Potassium channels and different states ofChara plasmalemma |
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Authors: | M J Beilby |
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Institution: | (1) Botany School, Cambridge University, CB2 3EA Cambridge, England;(2) Present address: School of Biological Sciences, University of Sydney, 2006 Sydney, N.S.W., Australia |
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Abstract: | 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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Keywords: | Chara corallina K+ channels I/V characteristics plasmalemma voltage clamp |
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