scholarly journals A generalized kinetic model describes ion-permeation mechanisms in various ion channels

2021 ◽  
Author(s):  
Di Wu
Keyword(s):  
Ion Channels ◽  
Kinetic Model ◽  
Patch Clamp ◽  
Cellular Responses ◽  
Ion Permeation ◽  
Patch Clamp Recording ◽  
Boltzmann Factor ◽  
Current Voltage ◽  
Test Voltage ◽  
Generalized Kinetic Model

Ion channels conduct various ions across biological membranes to maintain the membrane potential, to transmit the electrical signals, and to elicit the subsequent cellular responses by the signaling ions. Ion channels differ in their capabilities to select and conduct ions, which can be studied by the patch-clamp recording method that compares the current traces responding to the test voltage elicited at different conditions. In these experiments, the current-voltage curves are usually fitted by a sigmoidal function containing the Boltzmann factor. This equation is quite successful in fitting the experimental data in many cases, but it also fails in several others. Regretfully, some useful information may be lost in these data, which otherwise can reveal the ion-permeation mechanisms. Here we present a generalized kinetic model that captures the essential features of the current-voltage relations and describes the simple mechanism of the ion permeation through different ion channels. We demonstrate that this model is capable to fit various types of the patch-clamp data and explain their ion-permeation mechanisms.

Analyzing Ion Permeation in Channels and Pumps Using Patch-Clamp Recording

2015 ◽  
pp. 51-88 ◽  
Author(s):  
Andrew J. Moorhouse ◽  
Trevor M. Lewis ◽  
Peter H. Barry
Keyword(s):  
Patch Clamp ◽  
Ion Permeation ◽  
Patch Clamp Recording

Patch-Clamp Recording of Ion Channels: Interfering Effects of Patch Pipette Glass

Physiology ◽  
1990 ◽  
Vol 5 (4) ◽  
pp. 155-158
Author(s):  
C Zuazaga ◽  
A Steinacker
Keyword(s):  
Ion Channels ◽  
Patch Clamp ◽  
Ion Channel ◽  
Channel Activity ◽  
Patch Clamp Recording ◽  
Patch Clamp Technique ◽  
Clamp Technique ◽  
Ion Channel Properties ◽  
Patch Pipette ◽  
Channel Properties

Glass for pipettes used to record ion channel activity with the patch-clamp technique is selected on the basis of its electrical, thermal, and sealing properties. Recent findings stress a new characteristic to consider: the effect of pipette glass itself on ion channel properties.

Shock Wave Therapy as an Innovative Technology in Skeletal Disorders: Study on Transmembrane Current in Stimulated Osteoblast-Like Cells

2005 ◽  
Vol 28 (8) ◽  
pp. 841-847 ◽  
Author(s):  
L. Martini ◽  
G. Giavaresi ◽  
M. Fini ◽  
P. Torricelli ◽  
V. Borsari ◽  
...  
Keyword(s):  
Shock Wave ◽  
Ion Channels ◽  
Patch Clamp ◽  
Ionic Current ◽  
Innovative Technology ◽  
Patch Clamp Recording ◽  
Patch Clamp Technique ◽  
Transmembrane Current ◽  
Clamp Technique ◽  
And Control

Extracorporeal shock wave treatment (ESWT) is successfully used in various musculoskeletal disorders and pathologies. Despite the increasing use of this kind of therapy, some aspects of its mechanism of action are still unclear. In vitro bone cell behavior under ESWT were previously investigated by the present author and MG63 osteoblast-like cells showed an enhancement in proliferation and in the osteoblast differentiation after therapy with a low-energy flux density. The aim of the present study was to evaluate the effect of ESWT on the permeabilization of cell membrane. We characterized physiological changes in the MG63 associated with ESWT generated by an ESW device and patch clamp recording was performed to study ion channels. Experiments were carried out using the whole-cell recording configuration of the patch-clamp technique and the ionic current measurements were performed on cell samples of ESW treated and control groups. The patch-clamp technique showed the effect of ESWT on the amplitude of transmembrane currents. The treatment with ESW enhanced the transmembrane current as well the voltage dependence of Ca-activated and K channels that mediate these currents: the differences between treated cells and control at 80mV were over 1000 pA (P<0.05). These modifications of ion channels activity positively influence cell proliferation (MTT test, P<0.0001) without interfering with the normal synthesis activity of stimulated osteoblasts.

scholarly journals Theory and Experiments on Multi-Ion Permeation and Selectivity in the NaChBac Ion Channel

2019 ◽  
Vol 18 (02) ◽  
pp. 1940007 ◽  
Author(s):  
W. A. T. Gibby ◽  
M. L. Barabash ◽  
C. Guardiani ◽  
D. G. Luchinsky ◽  
O. A. Fedorenko ◽  
...  
Keyword(s):  
Statistical Theory ◽  
Ion Channels ◽  
Kinetic Model ◽  
Ion Channel ◽  
Linear Response ◽  
Unsolved Problem ◽  
Ion Permeation ◽  
Self Consistent ◽  
Self Consistency ◽  
Theory And Experiments

The highly selective permeation of ions through biological ion channels is an unsolved problem of noise and fluctuations. In this paper, we motivate and introduce a non-equilibrium and self-consistent multi-species kinetic model, with the express aims of comparing with experimental recordings of current versus voltage and concentration and extracting important permeation parameters. For self-consistency, the behavior of the model at the two-state, i.e., selective limit in linear response, must agree with recent results derived from an equilibrium statistical theory. The kinetic model provides a good fit to data, including the key result of an anomalous mole fraction effect.

scholarly journals A Novel Membrane Potential-Sensitive Fluorescent Dye Improves Cell-Based Assays for Ion Channels

2002 ◽  
Vol 7 (1) ◽  
pp. 79-85 ◽  
Author(s):  
Deborah F. Baxter ◽  
Martin Kirk ◽  
Amy F. Garcia ◽  
Alejandra Raimondi ◽  
Mats H. Holmqvist ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Ion Channels ◽  
Patch Clamp ◽  
High Throughput Screening ◽  
Fluorescent Dye ◽  
Patch Clamp Recording ◽  
Whole Cell ◽  
Cell Patch Clamp ◽  
Whole Cell Patch Clamp ◽  
Electrophysiological Studies

The study of ion channel-mediated changes in membrane potential using the conventional bisoxonol fluorescent dye DiBAC4(3) has several limitations, including a slow onset of response and multistep preparation, that limit both the fidelity of the results and the throughput of membrane potential assays. Here, we report the characterization of the FLIPR Membrane Potential Assay Kit (FMP) in cells expressing voltage- and ligand-gated ion channels. The steady-state and kinetics fluorescence properties of FMP were compared with those of DiBAC4(3), using both FLIPR and whole-cell patch-clamp recording. Our experiments with the voltage-gated K+ channel, hElk-1, revealed that FMP was 14-fold faster than DiBAC4(3) in response to depolarization. On addition of 60 mM KCl, the kinetics of fluorescence changes of FMP using FLIPR were identical to those observed in the electrophysiological studies using whole-cell current clamp. In addition, KCl concentration-dependent increases in FMP fluorescence correlated with the changes of membrane potential recorded in whole-cell patch clamp. In studies examining vanilloid receptor-1, a ligand-gated nonselective cation channel, FMP was superior to DiBAC4(3) with respect to both kinetics and amplitude of capsaicin-induced fluorescence changes. FMP has also been used to measure the activation of KATP1 and hERG.2 Thus this novel membrane potential dye represents a powerful tool for developing high-throughput screening assays for ion channels.

scholarly journals Characterization of ion channels and O2 sensitivity in gill neuroepithelial cells of the anoxia-tolerant goldfish (Carassius auratus)

2017 ◽  
Vol 118 (6) ◽  
pp. 3014-3023 ◽  
Author(s):  
Peter C. Zachar ◽  
Wen Pan ◽  
Michael G. Jonz
Keyword(s):  
Ion Channels ◽  
Patch Clamp ◽  
Synaptic Vesicle ◽  
Resting Membrane Potential ◽  
Patch Clamp Recording ◽  
Whole Cell ◽  
Neuroepithelial Cells ◽  
Voltage Dependent ◽  
Intracellular Ca

The neuroepithelial cell (NEC) of the fish gill is an important model for O2 sensing in vertebrates; however, a complete picture of the chemosensory mechanisms in NECs is lacking, and O2 chemoreception in vertebrates that are tolerant to anoxia has not yet been explored. Using whole cell patch-clamp recording, we characterized four types of ion channels in NECs isolated from the anoxia-tolerant goldfish. A Ca2+-dependent K+ current ( IKCa) peaked at ~20 mV, was potentiated by increased intracellular Ca2+, and was reduced by 100 μM Cd2+. A voltage-dependent inward current in Ba2+ solution, with peak at 0 mV, confirmed the presence of Ca2+ channels. A voltage-dependent K+ current ( IKV) was inhibited by 20 mM tetraethylammonium and 5 mM 4-aminopyridine, revealing a background K+ current ( IKB) with open rectification. Mean resting membrane potential of −45.2 ± 11.6 mV did not change upon administration of hypoxia (Po2 = 11 mmHg), nor were any of the K+ currents sensitive to changes in Po2 during whole cell recording. By contrast, when the membrane and cytosol were left undisturbed during fura-2 or FM 1-43 imaging experiments, hypoxia increased intracellular Ca2+ concentration and initiated synaptic vesicle activity. 100 μM Cd2+ and 50 μM nifedipine eliminated uptake of FM 1-43. We conclude that Ca2+ influx via L-type Ca2+ channels is correlated with vesicular activity during hypoxic stimulation. In addition, we suggest that expression of IKCa in gill NECs is species specific and, in goldfish, may contribute to an attenuated response to acute hypoxia. NEW & NOTEWORTHY This study provides the first physiological characterization of oxygen chemoreceptors from an anoxia-tolerant vertebrate. Neuroepithelial cells (NECs) from the gills of goldfish displayed L-type Ca2+ channels and three types of K+ channels, one of which was dependent upon intracellular Ca2+. Although membrane currents were not inhibited by hypoxia during patch-clamp recording, this study is the first to show that NECs with an undisturbed cytosol responded to hypoxia with increased intracellular Ca2+ and synaptic vesicle activity.

On the superposition of currents from ion channels

1991 ◽  
Vol 334 (1271) ◽  
pp. 347-356 ◽  
Keyword(s):  
Ion Channels ◽  
Patch Clamp ◽  
Dwell Time ◽  
Statistical Properties ◽  
Patch Clamp Recording ◽  
The Individual

We derive a number of statistical properties of the superposition of several independent channels contributing to a patch-clamp recording. Failure of these properties indicates dependence of the channels and may suggest the nature of interactions. We show how properties such as dwell-time distributions of the individual channels may be determined from those of the superposition in the case that the channels are independent.

scholarly journals CellSpecks: A Software for Automated Detection and Analysis of Calcium Channels in Live Cells

2018 ◽  
Author(s):  
S I Shah ◽  
M Smith ◽  
D Swaminathan ◽  
I Parker ◽  
G Ullah ◽  
...  
Keyword(s):  
Ion Channels ◽  
Patch Clamp ◽  
Nicotinic Acetylcholine Receptors ◽  
High Throughput Screening ◽  
Single Channel ◽  
Video Recording ◽  
Synthetic Data ◽  
Live Cells ◽  
Patch Clamp Recording ◽  
Additional Advantage

ABSTRACTTo couple the fidelity of patch-clamp recording with a more high-throughput screening capability, we pioneered a novel approach to single channel recording that we named “optical patch clamp”. By using highly-sensitive fluorescent Ca2+ indicator dyes in conjunction with total internal fluorescence microscopy techniques, we monitor Ca2+ flux through individual Ca2+-permeable channels. This approach provides information about channel gating analogous to patch-clamp recording at time resolution of ~ 2 ms, with the additional advantage of being massively parallel, providing simultaneous and independent recording from thousands of channels in native environment. However, manual analysis of the data generated by this technique presents severe challenges as a video recording can include many thousands of frames. To overcome this bottleneck, we developed an image processing and analysis framework called CellSpecks, capable of detecting and fully analyzing the kinetics of ion channels within a video sequence. By using a randomly generated synthetic data, we tested the ability of CellSpecks to rapidly and efficiently detect and analyze the activity of thousands of ion channels, including openings for a few milliseconds. Here, we report the use of CellSpecks for the analysis of experimental data acquired by imaging muscle nicotinic acetylcholine receptors and the Alzheimer’s disease-associated amyloid beta pores with multiconductance levels in the plasma membrane of Xenopus laevis oocytes. We show that CellSpecks can accurately and efficiently generate location maps, create raw and processed fluorescence time-traces, histograms of mean open times, mean close times, open probabilities, durations, and maximum amplitudes, and a ‘channel chip’ showing the activity of all channels as a function of time. Although we specifically illustrate the application of CellSpecks for analyzing data from Ca2+ channels, it can be easily customized to analyze other spatially and temporally localized signals.

Measurement of spontaneous neuronal membrane activity by time lapse confocal microscopy

1995 ◽  
Vol 53 ◽  
pp. 972-973
Author(s):  
R H. Selinfreund ◽  
A. H. Cornell-Bell
Keyword(s):  
Membrane Potential ◽  
Confocal Microscopy ◽  
Patch Clamp ◽  
Electrical Activity ◽  
Time Lapse ◽  
Neuronal Firing ◽  
Neuronal Membrane ◽  
Pituitary Cells ◽  
Patch Clamp Recording ◽  
Spontaneous Electrical Activity

Cellular electrophysiological properties are normally monitored by standard patch clamp techniques . The combination of membrane potential dyes with time-lapse laser confocal microscopy provides a more direct, least destructive rapid method for monitoring changes in neuronal electrical activity. Using membrane potential dyes we found that spontaneous action potential firing can be detected using time-lapse confocal microscopy. Initially, patch clamp recording techniques were used to verify spontaneous electrical activity in GH4\C1 pituitary cells. It was found that serum depleted cells had reduced spontaneous electrical activity. Brief exposure to the serum derived growth factor, IGF-1, reconstituted electrical activity. We have examined the possibility of developing a rapid fluorescent assay to measure neuronal activity using membrane potential dyes. This neuronal regeneration assay has been adapted to run on a confocal microscope. Quantitative fluorescence is then used to measure a compounds ability to regenerate neuronal firing.The membrane potential dye di-8-ANEPPS was selected for these experiments. Di-8- ANEPPS is internalized slowly, has a high signal to noise ratio (40:1), has a linear fluorescent response to change in voltage.

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