Voltage clamping with single microelectrodes: Comparison of the discontinuous mode and continuous mode using the Axoclamp 2A amplifier |
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Authors: | R Y K Pun |
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Institution: | (1) Department of Physiology and Biophysics, University of Cincinnati, College of Medicine, 45267-0576 Cincinnati, OH, USA |
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Abstract: | Summary The voltage clamp technique is a powerful method for studying the physiology of excitable membrane. This technique has made possible the determination of ionic responses generated by activation of either receptor-mediated or voltage-dependent processes. The development of the whole-cell, tight-seal voltage clamp method has allowed the analysis and examination of membrane physiology at the single cell level. The method allows the characterization of voltage-dependent ionic conductances both at the macroscopic (whole-cell) and at the microscopic (unitary conductance or single channel) level in cells less than 10 µm in diameter, a feat difficult to achieve with conventional fine-tipped micropipettes.In this paper, several methologies used for culturing neuronal and non-neuronal cells in the laboratory are described. A comparison between the two modes of voltage clamp using blunt-tipped patch-microelectrodes, the switching (discontinuous) and the non-switching (continuous) modes, of the Axoclamp-2A amplifier is made. Some results on membrane currents obtained from neuronal and non-neuronal cells using the single electrode whole-cell tight-seal voltage clamp is illustrated. The possible existence of two inactivating K+ currents, one dependent on Ca++ the other is not, is discussed. |
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Keywords: | voltage clamp neurons PC12 inactivating Ca++-dependent K+ current Ca++ current tissue culture |
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