Discontinuous single electrode voltage‐clamp measurements: assessment of clamp accuracy in Vicia faba guard cells

The use of a discontinuous single electrode voltage‐clamp (dSEVC) offers an attractive alternative to the patch‐clamp technique, since whole‐cell measurements can be performed with a single sharp electrode. Comparison of current–voltage relations, however, revealed a weaker voltage dependence of cha...

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Bibliographic Details
Published in:Journal of experimental botany 2001-09, Vol.52 (362), p.1933-1939
Main Authors: Roelfsema, M.R.G., Steinmeyer, Ralf, Hedrich, Rainer
Format: Article
Language:English
Subjects:
Amplifiers
Biological and medical sciences
Capacitance
Cell Membrane
Cell membranes
Cell physiology
Clamping devices
Current voltage characteristics
Discontinuous single electrode voltage clamp
Electric conductance
Electric current
Electric potential
Electrodes
Fabaceae - physiology
Fundamental and applied biological sciences. Psychology
guard cell
Guard cells
Ion Channels
Ionic conduction
Kinetics
Membrane potential
Membrane Potentials
Methods Papers
Microelectrodes
Patch-Clamp Techniques - methods
plant cell
Plant cells
Plant Epidermis - physiology
Plant physiology and development
Plant Structures - physiology
Plasma currents
Plasma membrane and permeation
Potassium - metabolism
Voltage measurement
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Summary:The use of a discontinuous single electrode voltage‐clamp (dSEVC) offers an attractive alternative to the patch‐clamp technique, since whole‐cell measurements can be performed with a single sharp electrode. Comparison of current–voltage relations, however, revealed a weaker voltage dependence of channels measured with the dSEVC compared to patch clamp. The accuracy of the dSEVC was tested on Vicia faba guard cells impaled with double‐barrelled electrodes. The actual clamp potential was measured independently of the dSEVC, at the second barrel. The weaker voltage dependence of ion channels appeared to be due to an overestimation of the clamp potential by the dSEVC. The deviation between the intended and actual clamp potential showed a linear relationship with the injected current; on average a 126 mV deviation was found for a clamp current of 1 nA. The deviation was probably caused by a slow settling capacity at the electrode, not compensated by the dSEVC amplifier. It is concluded that the dSEVC method in its current state is only suited for the study of small ion conductances in plant cells.
ISSN:0022-0957
1460-2431
DOI:10.1093/jexbot/52.362.1933