title: Determination and compensation of series resistances during whole-cell patch-clamp recordings using an active bridge circuit and the phase-sensitive technique.
abstract: We present a technique which combines two methods in order to measure the series resistance (R S) during whole-cell patch-clamp recordings from excitable and non-excitable cells. R S is determined in the amplifier's current-clamp mode by means of an active bridge circuit. The correct neutralization of the electrode capacitance and the adjustment of the bridge circuit is achieved by the so-called phase-sensitive method: Short sine wave currents with frequencies between 3 and 7 kHz are injected into the cells. Complete capacitance neutralization is indicated by the disappearance of the phase lag between current and voltage, and correct bridge balance is indicated by a minimized voltage response to the sine wave current. The R S value determined in the current-clamp mode then provides the basis for R S compensation in the voltage-clamp recording mode. The accuracy of the procedure has been confirmed on single-compartment cell models where the error amounted to 2-3 %. Similar errors were observed during dual patch clamp recordings from single neocortical layer 5 pyramidal cells where one electrode was connected to the bridge amplifier and the other one to a time-sharing, single-electrode current- and voltage-clamp amplifier with negligible R S. The technique presented here allows R S compensation for up to 80-90 %, even in cells with low input resistances (e.g., astrocytes). In addition, the present study underlines the importance of correct R S compensation by showing that significant series resistances directly affect the determination of membrane conductances as well as the kinetic properties of spontaneous synaptic currents with small amplitudes.
authors.affiliation: BioMedizinisches Centrum (BMC), Ludwig-Maximilians-University (LMU), Physiological Genomics, Physiological Institute, Großhaderner Str. 9, 82152, Planegg, Germany.
authors.forename: Therese
authors.initials: T
authors.lastname: Riedemann
authors.affiliation: npi electronic GmbH, Bauhofring 16, 71732, Tamm, Germany.
authors.forename: Hans Reiner
authors.initials: HR
authors.lastname: Polder
authors.affiliation: BioMedizinisches Centrum (BMC), Ludwig-Maximilians-University (LMU), Physiological Genomics, Physiological Institute, Großhaderner Str. 9, 82152, Planegg, Germany. bernd.sutor@lrz.uni-muenchen.de.
authors.forename: Bernd
authors.identifier: 0000-0002-9146-4438
authors.initials: B
authors.lastname: Sutor
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000502:physiology; D002478:Cells, Cultured; D051379:Mice; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques / Q000295:instrumentation / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley
keywords: Astrocytes; Bridge amplifier; Neurons; Series resistance; Whole-cell patch-clamp