Perforated Whole-Cell Recordings in Automated Patch Clamp Electrophysiology

2020 ◽  
pp. 93-108
Author(s):  
Kadla R. Rosholm ◽  
Kim Boddum ◽  
Anders Lindquist
Keyword(s):  
Patch Clamp ◽  
Whole Cell ◽  
Automated Patch Clamp ◽  
Patch Clamp Electrophysiology ◽  
Whole Cell Recordings

A patch-clamp study: secretagogue-induced currents in rat peritoneal mast cells

1989 ◽  
Vol 256 (3) ◽  
pp. C560-C568 ◽  
Author(s):  
M. Kuno ◽  
T. Okada ◽  
T. Shibata
Keyword(s):  
Mast Cells ◽  
Patch Clamp ◽  
Reversal Potential ◽  
Whole Cell ◽  
Current Voltage ◽  
Peritoneal Mast Cells ◽  
Induced Currents ◽  
Rat Peritoneal Mast Cells ◽  
Whole Cell Recordings ◽  
Current Voltage Relation

Ca2+ entry through plasma membrane has been considered to play a significant role in elevating cytosolic free Ca2+ concentrations during stimulus-secretion coupling in mast cells, but electrophysiological evidence of the Ca2+ channels is lacking. We examined the properties of secretagogue (compound 48/80)-induced currents in rat peritoneal mast cells, using the patch-clamp technique. In the whole cell recordings, the addition of compound 48/80 induced transient currents that were suppressed by Cd or reduced by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). In Ringer solution containing 2 mM Ca2+, the current-voltage relation was fairly linear from -100 to 50 mV and the reversal potential was 14 +/- 10.1 mV (n = 9). When the external Ca2+ was approximately 1 microM, the compound 48/80-induced currents were marginal, but readmission of Ca2+ or Ba2+ to the bath solution led to an appearance of the currents. In the cell-attached patches, the stimulation enhanced the activity of inward current mediated by Ba2+. The unitary inward Ba2+ current was characterized by the unitary conductance of 10.5 +/- 2.0 pS (n = 10) with isotonic BaCl2 pipette solution, the extrapolated reversal potential of 60.7 +/- 16.0 mV (n = 10) positive to the resting membrane potentials. The percent open time of the inward Ba2+ current channel was not appreciably changed by voltage. In some whole cell recordings, an increase in openings of the cation-selective channel (20-45 pS) was identified in the stimulated cells. When the external Na+ was completely replaced by choline+, the compound 48/80-induced currents had a fairly linear current-voltage relation.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals A Yoda1-Based Approach to Investigate Piezo1 Channels in Red Blood Cells Using Automated Patch Clamp Technology

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1031-1031
Author(s):  
Maria Giustina Rotordam ◽  
Elisa Fermo ◽  
Nadine Becker ◽  
Wilma Barcellini ◽  
Andrea Brüggemann ◽  
...  
Keyword(s):  
Shear Stress ◽  
Patch Clamp ◽  
Ion Channel ◽  
Red Blood Cells ◽  
High Throughput ◽  
Blood Cells ◽  
Screening Assay ◽  
Whole Cell ◽  
Automated Patch Clamp ◽  
Induced Currents

Abstract Piezo1 is a mechanosensitive ion channel supposed to regulate the volume and maintain the structural integrity in Red Blood Cells (RBCs), as gain-of-function mutations in this channel are associated to the RBC disease Hereditary Xerocytosis (Zarychanski et al. Blood 2012; Bae et al. Proceedings of the National Academy of Sciences 2013). Piezo1 is activated by several mechanical forces, including stretching, poking and shear stress and allows Ca2+ and other cations to enter the cell generating an electrical response. In 2015, it has been discovered that Piezo1 is sensitive to a small molecule, Yoda1 (Syeda et al. Elife 2015), which keeps the channel open and affects its inactivation kinetics. This finding has created new possibilities to elucidate Piezo1 gating mechanism and explore its functional significance in physiological and pathophysiological conditions. Here, we present a patient with a novel PIEZO1 mutation (R2110W) and a patch clamp-based high-throughput screening assay for Piezo1 activity. We established a protocol to detect functional Piezo1 mutations upon chemical stimulation by Yoda1, yet were not able to stimulate the channel via mechanical force, i.e. pressure steps and shear-stress. The assay was first developed on Neuro2A (N2A), a neuroblastoma cell-line endogenously expressing Piezo1 channels (kindly provided by Max-Delbrück Center, Berlin), due to larger abundance of Piezo1 channels in these cells. Initial experiments were performed on the Patchliner (Nanion Technologies GmbH, Munich), a medium-throughput automated patch clamp system able to record up to 8 cells at a time. Currents were elicited using a voltage ramp ranging from -100 to +80 mV for 300 ms, the holding potential was set to -60 mV. A significantly increased whole-cell current was observed upon 10 µM Yoda1 application in half of the recorded cells and the resulting Yoda1-induced currents were inhibited by 30 µM gadolinium chloride, a non-specific blocker of stretch-activated channels. The assay was then implemented on the SyncroPatch 384PE (Nanion Technologies GmbH, Munich), capable of recording up to 384 cells in parallel under identical experimental conditions, thus allowing for reliable statistical analysis. Yoda1 responding cells were selected based on strict quality control (QC) criteria, i.e. the seal resistance stability over time. In one example NPC-384 chip 140 out of 384 N2A cells (37%) passed the QC criteria and 85 cells (60% of the valid cells) were considered as Yoda1 responders. Finally, we investigated Piezo1 electrophysiological properties in healthy and patient RBCs carrying the novel PIEZO1 R2110W mutation. Similar to N2A cells, RBCs currents were analyzed and divided into Yoda1 responders and non-responders according to our QC criteria. The increase in whole-cell currents induced by Yoda1 application was significantly higher in patient compared to control RBCs, which was also reflected by a higher number of Yoda1 responders compared to control. Residue R2110W is structurally located in a gating sensitive area of the channel protein suggesting a gain-of-function. This would be in line with previously described mutations in PIEZO1 (Albuisson et al. Nature Communications 2013) and the mild form of anaemia observed in the patient. Furthermore, we excluded any involvement of Gardos channels in the Yoda1-induced currents by comparing measurements in the presence and absence of the specific Gardos channel inhibitor TRAM-34. Altogether, our work demonstrates that high-throughput patch clamping can provide a robust assay to study functional Piezo1 impairments in primary RBCs without expressing the mutated channel protein in a heterologous expression system. Our approach may be used to detect other channelopathies not only in RBCs and may serve as routine screening assay for diseases related to ion channel dysfunctions in general, complementary to gene sequencing. Disclosures No relevant conflicts of interest to declare.

scholarly journals Robotic Automation of In Vivo Two-Photon Targeted Whole-Cell Patch-Clamp Electrophysiology

Neuron ◽  
2017 ◽  
Vol 95 (5) ◽  
pp. 1048-1055.e3 ◽  
Author(s):  
Luca A. Annecchino ◽  
Alexander R. Morris ◽  
Caroline S. Copeland ◽  
Oshiorenoya E. Agabi ◽  
Paul Chadderton ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Whole Cell ◽  
Two Photon ◽  
Cell Patch Clamp ◽  
Whole Cell Patch Clamp ◽  
Patch Clamp Electrophysiology ◽  
Robotic Automation

scholarly journals Automated Patch-Clamp Technique: Increased Throughput in Functional Characterization and in Pharmacological Screening of Small-Conductance Ca2+ Release-Activated Ca2+ Channels

2008 ◽  
Vol 13 (7) ◽  
pp. 638-647 ◽  
Author(s):  
Rikke L. Schrøder ◽  
Søren Friis ◽  
Morten Sunesen ◽  
Chris Mathes ◽  
Niels J. Willumsen
Keyword(s):  
Patch Clamp ◽  
Calcium Release ◽  
Functional Characterization ◽  
High Signal ◽  
Patch Clamp Technique ◽  
Whole Cell ◽  
Crac Channels ◽  
Current Activation ◽  
Automated Patch Clamp ◽  
Pharmacological Screening

The suitability of an automated patch clamp for the characterization and pharmacological screening of calcium release—activated calcium (CRAC) channels endogenously expressed in RBL-2H3 cells was explored with the QPatch system. CRAC currents (I CRAC) are small, and thus precise recordings require high signal-to-noise ratios obtained by high seal resistances. Automated whole-cell establishment resulted in membrane resistances of 1728 ± 226 MΩ ( n = 44). CRAC channels were activated by a number of methods that raise intracellular calcium concentration, including EGTA, ionomycin, Ins(1,4,5)P3, and thapsigargin. ICRAC whole-cell currents ranged from 30 to 120 pA with rise times of 40 to 150 s. An initial delay in current activation was observed in particular when ICRAC was activated by passive store depletion using EGTA. Apparent rundown of ICRAC was commonly observed, and the current could be reactivated by subsequent addition of thapsigargin. ICRAC was blocked by SKF-96365 and 2-APB with IC50 values of 4.7 ± 1.1 µM ( n = 9) and 7.5 ± 0.7 ( n = 9) µM, respectively. The potencies of these blockers were similar to values reported for ICRAC in similar conventional patch-clamp experiments. The study demonstrates that CRAC channels can be rapidly and efficiently targeted with automated patch-clamp techniques for characterization of physiological and pharmacological properties. ( Journal of Biomolecular Screening 2008:638-647)

scholarly journals Heterozygous KCNH2 variant phenotyping using Flp-In HEK293 and high-throughput automated patch clamp electrophysiology

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Chai-Ann Ng ◽  
Jessica Farr ◽  
Paul Young ◽  
Monique J Windley ◽  
Matthew D Perry ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Cell Lines ◽  
High Throughput ◽  
Rapid Assessment ◽  
Cost Effective ◽  
Missense Variant ◽  
Loss Of Function ◽  
Channel Expression ◽  
Automated Patch Clamp ◽  
Patch Clamp Electrophysiology

Abstract KCNH2 is one of the 59 medically actionable genes recommended by the American College of Medical Genetics for reporting of incidental findings from clinical genomic sequencing. However, half of the reported KCNH2 variants in the ClinVar database are classified as variants of uncertain significance. In the absence of strong clinical phenotypes, there is a need for functional phenotyping to help decipher the significance of variants identified incidentally. Here, we report detailed methods for assessing the molecular phenotype of any KCNH2 missense variant. The key components of the assay include quick and cost-effective generation of a bi-cistronic vector to co-express Wild-type (WT) and any KCNH2 variant allele, generation of stable Flp-In HEK293 cell lines and high-throughput automated patch clamp electrophysiology analysis of channel function. Stable cell lines take 3–4 weeks to produce and can be generated in bulk, which will then allow up to 30 variants to be phenotyped per week after 48 h of channel expression. This high-throughput functional genomics assay will enable a much more rapid assessment of the extent of loss of function of any KCNH2 variant.

scholarly journals Analysis of neuronal Ca2+ handling properties by combining perforated patch clamp recordings and the added buffer approach

2020 ◽  
Author(s):  
Simon Hess ◽  
Christophe Pouzat ◽  
Lars Paeger ◽  
Andreas Pippow ◽  
Peter Kloppenburg
Keyword(s):  
Patch Clamp ◽  
Intracellular Signaling ◽  
Whole Cell ◽  
Perforated Patch ◽  
Cellular Processes ◽  
Wide Range ◽  
Intracellular Ca ◽  
Precise Quantification ◽  
Perforated Patch Clamp ◽  
Whole Cell Recordings

AbstractCa2+ functions as an important intracellular signal for a wide range of cellular processes. These processes are selectively activated by controlled spatiotemporal dynamics of the free cytosolic Ca2+. Intracellular Ca2+ dynamics are regulated by numerous cellular parameters. Here, we established a new way to determine neuronal Ca2+ handling properties by combining the ‘added buffer’ approach (Neher and Augustine, 1992) with perforated patch-clamp recordings (Horn and Marty, 1988). Since the added buffer approach typically employs the standard whole-cell configuration for concentration-controlled Ca2+ indicator loading, it only allows for the reliable estimation of the immobile fraction of intracellular Ca2+ buffers. Furthermore, crucial components of intracellular signaling pathways are being washed out during prolonged whole-cell recordings, leading to cellular deterioration. By combining the added buffer approach with perforated patch-clamp recordings, these issues are circumvented, allowing the precise quantification of the cellular Ca2+ handling properties, including immobile as well as mobile Ca2+ buffers.

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