Introduction: patch clamp and single-cell voltage clamp techniques and selected data

1989 ◽  
Vol 80 (1-2) ◽  
Author(s):  
Nicholas Sperelakis
Keyword(s):  
Patch Clamp ◽  
Single Cell ◽  
Voltage Clamp ◽  
Cell Voltage

Constant-potential environment for activating and synchronizing cardiomyocyte colonies with on-chip ion-depleting perm-selective membranes

Lab on a Chip ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 4273-4284
Author(s):  
Vivek Yadav ◽  
Nicholas Chong ◽  
Bradley Ellis ◽  
Xiang Ren ◽  
Satyajyoti Senapati ◽  
...  
Keyword(s):  
Ion Channel ◽  
Single Cell ◽  
Voltage Clamp ◽  
Cell Voltage ◽  
Extracellular Potential ◽  
Constant Potential ◽  
On Chip ◽  
Selective Membranes

An ion depleted zone was used to impose a high and uniform constant extracellular potential over an entire ∼1000 cell rat cardiomyocyte (rCM) colony on-a-chip, extending single-cell voltage-clamp ion channel studies to an entire normalized colony.

scholarly journals Rapid characterisation of hERG channel kinetics I: using an automated high-throughput system

2019 ◽  
Author(s):  
Chon Lok Lei ◽  
Michael Clerx ◽  
David J. Gavaghan ◽  
Liudmila Polonchuk ◽  
Gary R. Mirams ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Single Cell ◽  
Voltage Clamp ◽  
High Throughput ◽  
Rapid Development ◽  
Herg Channel ◽  
Model Parameters ◽  
Channel Kinetics ◽  
Automated Patch Clamp ◽  
High Information

ABSTRACTPredicting how pharmaceuticals may affect heart rhythm is a crucial step in drug-development, and requires a deep understanding of a compound’s action on ion channels.In vitrohERG-channel current recordings are an important step in evaluating the pro-arrhythmic potential of small molecules, and are now routinely performed using automated high-throughput patch clamp platforms. These machines can execute traditional voltage clamp protocols aimed at specific gating processes, but the array of protocols needed to fully characterise a current is typically too long to be applied in a single cell. Shorter high-information protocols have recently been introduced which have this capability, but they are not typically compatible with high-throughput platforms. We present a new high-information 15 s protocol to characterise hERG (Kv11.1) kinetics, suitable for both manual and high-throughput systems. We demonstrate its use on the Nanion SyncroPatch 384PE, a 384 well automated patch clamp platform, by applying it to CHO cells stably expressing hERG1a. From these recordings we construct 124 cell-specific variants/parameterisations of a hERG model at 25 °C. A further 8 independent protocols are run in each cell, and are used to validate the model predictions. We then combine the experimental recordings using a hierarchical Bayesian model, which we use to quantify the uncertainty in the model parameters, and their variability from cell to cell, which we use to suggest reasons for the variability. This study demonstrates a robust method to measure and quantify uncertainty, and shows that it is possible and practical to use high-throughput systems to capture full hERG channel kinetics quantitatively and rapidly.Statement of SignificanceWe present a method for high-throughput characterisation of hERG potassium channel kinetics, via fitting a mathematical model to results of over one hundred single cell patch clamp measurements collected simultaneously on an automated voltage clamp platform. The automated patch clamp data are used to parameterise a mathematical ion channel model fully, opening a new era of automated and rapid development of mathematical models from quick and cheap experiments. The method also allows ample data for independent validation of the models and enables us to study experimental variability and propose its origins. In future the method can be applied to characterise changes to hERG currents in different conditions, for instance at different temperatures (see Part II of the study) or under mutations or the action of pharmaceuticals; and should be easily adapted to study many other currents.

scholarly journals Computer modeling of whole-cell voltage-clamp analyses to delineate guidelines for good practice of manual and automated patch-clamp

2020 ◽  
Author(s):  
Jérôme Montnach ◽  
Maxime Lorenzini ◽  
Adrien Lesage ◽  
Isabelle Simon ◽  
Sébastien Nicolas ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Voltage Clamp ◽  
Good Practice ◽  
Cell Voltage ◽  
Current Amplitude ◽  
Patch Clamp Technique ◽  
Whole Cell ◽  
Clamp Technique ◽  
Whole Cell Voltage Clamp

ABSTRACTThe patch-clamp technique has contributed to major advances in the characterization of ion channels. The recent development of high throughput patch-clamp provides a new momentum to the field. However, whole-cell voltage-clamp technique presents certain limits that need to be considered for robust data generation. One major caveat is that current amplitude profoundly impacts the precision of the analyzed characteristics of the ion current under study. For voltagegated channels, the higher the current amplitude is, the less precise the characteristics of voltagedependence are. Similarly, in ion channel pharmacology, the characteristics of dose-response curves are hindered by high current amplitudes. In addition, the recent development of high throughput patch-clamp technique is often associated with the generation of stable cell lines demonstrating high current amplitudes. It is therefore critical to set the limits for current amplitude recordings to avoid inaccuracy in the characterization of channel properties or drug actions, such limits being different from one channel to another. In the present study, we use kinetic models of a voltage-gated sodium channel and a voltage-gated potassium channel to edict simple guidelines for good practice of whole-cell voltage-clamp recordings.

scholarly journals Computer modeling of whole-cell voltage-clamp analyses to delineate guidelines for good practice of manual and automated patch-clamp

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jérôme Montnach ◽  
Maxime Lorenzini ◽  
Adrien Lesage ◽  
Isabelle Simon ◽  
Sébastien Nicolas ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Voltage Clamp ◽  
Good Practice ◽  
Cell Voltage ◽  
Current Amplitude ◽  
Patch Clamp Technique ◽  
Whole Cell ◽  
Clamp Technique ◽  
Whole Cell Voltage Clamp

AbstractThe patch-clamp technique and more recently the high throughput patch-clamp technique have contributed to major advances in the characterization of ion channels. However, the whole-cell voltage-clamp technique presents certain limits that need to be considered for robust data generation. One major caveat is that increasing current amplitude profoundly impacts the accuracy of the biophysical analyses of macroscopic ion currents under study. Using mathematical kinetic models of a cardiac voltage-gated sodium channel and a cardiac voltage-gated potassium channel, we demonstrated how large current amplitude and series resistance artefacts induce an undetected alteration in the actual membrane potential and affect the characterization of voltage-dependent activation and inactivation processes. We also computed how dose–response curves are hindered by high current amplitudes. This is of high interest since stable cell lines frequently demonstrating high current amplitudes are used for safety pharmacology using the high throughput patch-clamp technique. It is therefore critical to set experimental limits for current amplitude recordings to prevent inaccuracy in the characterization of channel properties or drug activity, such limits being different from one channel type to another. Based on the predictions generated by the kinetic models, we draw simple guidelines for good practice of whole-cell voltage-clamp recordings.

scholarly journals Degradation Investigation of Electrocatalyst in Proton Exchange Membrane Fuel Cell at a High Energy Efficiency

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3932
Author(s):  
Jie Song ◽  
Qing Ye ◽  
Kun Wang ◽  
Zhiyuan Guo ◽  
Meiling Dou
Keyword(s):  
Energy Efficiency ◽  
Single Cell ◽  
Proton Exchange Membrane ◽  
Cell Voltage ◽  
High Energy ◽  
Proton Exchange ◽  
Pt Catalyst ◽  
Operation Conditions ◽  
High Efficient ◽  
Exchange Membrane

The development of high efficient stacks is critical for the wide spread application of proton exchange membrane fuel cells (PEMFCs) in transportation and stationary power plant. Currently, the favorable operation conditions of PEMFCs are with single cell voltage between 0.65 and 0.7 V, corresponding to energy efficiency lower than 57%. For the long term, PEMFCs need to be operated at higher voltage to increase the energy efficiency and thus promote the fuel economy for transportation and stationary applications. Herein, PEMFC single cell was investigated to demonstrate its capability to working with voltage and energy efficiency higher than 0.8 V and 65%, respectively. It was demonstrated that the PEMFC encountered a significant performance degradation after the 64 h operation. The cell voltage declined by more than 13% at the current density of 1000 mA cm−2, due to the electrode de-activation. The high operation potential of the cathode leads to the corrosion of carbon support and then causes the detachment of Pt nanoparticles, resulting in significant Pt agglomeration. The catalytic surface area of cathode Pt is thus reduced for oxygen reduction and the cell performance decreased. Therefore, electrochemically stable Pt catalyst is highly desirable for efficient PEMFCs operated under cell voltage higher than 0.8 V.

Developmental change in fast Na channel properties in embryonic chick ventricular heart cells

1995 ◽  
Vol 73 (10) ◽  
pp. 1475-1484 ◽  
Author(s):  
Hideaki Sada ◽  
Takashi Ban ◽  
Takeshi Fujita ◽  
Yoshio Ebina ◽  
Nicholas Sperelakis
Keyword(s):  
Steady State ◽  
Voltage Clamp ◽  
Time Constant ◽  
Voltage Dependence ◽  
Cell Voltage ◽  
Developmental Changes ◽  
Heart Cells ◽  
Embryonic Chick ◽  
Whole Cell ◽  
Whole Cell Voltage Clamp

To assess developmental changes in kinetic properties of the cardiac sodium current, whole-cell voltage-clamp experiments were conducted using 3-, 10-, and 17-day-old embryonic chick ventricular heart cells. Experimental data were quantified according to the Hodgkin–Huxley model. While the Na current density, as examined by the maximal conductance, drastically increased (six- to seven-fold) with development, other current–voltage parameters remained unchanged. Whereas the activation time constant and the steady-state activation characteristics were comparable among the three age groups, the voltage dependence of the inactivation time constant and the steady-state inactivation underwent a shift in the voltage dependence toward negative potentials during embryonic development. Consequently, the steady-state (window current) conductance, which was sufficient to induce automatic activity in the young embryos, was progressively reduced with age.Key words: cardiac electrophysiology, whole-cell voltage-clamp experiments, fast Na currents, heart, development, developmental changes.

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