Multichannel detection of ionic currents through two nanopores fabricated on integrated Si3N4 membranes

Lab on a Chip ◽  
2016 ◽  
Vol 16 (17) ◽  
pp. 3340-3350 ◽  
Author(s):  
Itaru Yanagi ◽  
Rena Akahori ◽  
Mayu Aoki ◽  
Kunio Harada ◽  
Ken-ichi Takeda
Keyword(s):  
Ionic Current ◽  
Ionic Currents ◽  
Multichannel Detection ◽  
Signal Crosstalk

We demonstrated the simultaneous multichannel detections of clear ionic-current blockades without signal crosstalk when poly(dA)60 passed through two nanopores.

scholarly journals Anoctamin 5/TMEM16E facilitates muscle precursor cell fusion

2018 ◽  
Vol 150 (11) ◽  
pp. 1498-1509 ◽  
Author(s):  
Jarred M. Whitlock ◽  
Kuai Yu ◽  
Yuan Yuan Cui ◽  
H. Criss Hartzell
Keyword(s):  
Cell Fusion ◽  
Ionic Current ◽  
Ionic Currents ◽  
Muscle Physiology ◽  
Muscle Repair ◽  
Hek 293 ◽  
293 Cells ◽  
Phospholipid Scrambling ◽  
Muscle Precursor Cell

Limb-girdle muscular dystrophy type 2L (LGMD2L) is a myopathy arising from mutations in ANO5; however, information about the contribution of ANO5 to muscle physiology is lacking. To explain the role of ANO5 in LGMD2L, we previously hypothesized that ANO5-mediated phospholipid scrambling facilitates cell–cell fusion of mononucleated muscle progenitor cells (MPCs), which is required for muscle repair. Here, we show that heterologous overexpression of ANO5 confers Ca2+-dependent phospholipid scrambling to HEK-293 cells and that scrambling is associated with the simultaneous development of a nonselective ionic current. MPCs isolated from adult Ano5−/− mice exhibit defective cell fusion in culture and produce muscle fibers with significantly fewer nuclei compared with controls. This defective fusion is associated with a decrease of Ca2+-dependent phosphatidylserine exposure on the surface of Ano5−/− MPCs and a decrease in the amplitude of Ca2+-dependent outwardly rectifying ionic currents. Viral introduction of ANO5 in Ano5−/− MPCs restores MPC fusion competence, ANO5-dependent phospholipid scrambling, and Ca2+-dependent outwardly rectifying ionic currents. ANO5-rescued MPCs produce myotubes having numbers of nuclei similar to wild-type controls. These data suggest that ANO5-mediated phospholipid scrambling or ionic currents play an important role in muscle repair.

scholarly journals Differential Inhibitory Actions of Multitargeted Tyrosine Kinase Inhibitors on Different Ionic Current Types in Cardiomyocytes

2020 ◽  
Vol 21 (5) ◽  
pp. 1672 ◽  
Author(s):  
Wei-Ting Chang ◽  
Ping-Yen Liu ◽  
Kaisen Lee ◽  
Yin-Hsun Feng ◽  
Sheng-Nan Wu
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitors ◽  
Kinase Inhibitors ◽  
Ionic Current ◽  
Small Animal ◽  
Ionic Currents ◽  
Neonatal Rat ◽  
Delayed Rectifier ◽  
Qtc Prolongation ◽  
The Impact

Lapatinib (LAP) and sorafenib (SOR) are multitargeted tyrosine kinase inhibitors (TKIs) with antineoplastic properties. In clinical observations, LAP and SOR may contribute to QTc prolongation, but the detailed mechanism for this has been largely unexplored. In this study, we investigated whether LAP and SOR affect the activities of membrane ion channels. Using a small animal model and primary cardiomyocytes, we studied the impact of LAP and SOR on Na+ and K+ currents. We found that LAP-induced QTc prolongation in mice was reversed by isoproterenol. LAP or SOR suppressed the amplitude of the slowly activating delayed-rectifier K+ current (IK(S)) in H9c2 cells in a time- and concentration-dependent fashion. The LAP-mediated inhibition of IK(S) was reversed by adding isoproterenol or meclofenamic acid, but not by adding diazoxide. The steady-state activation curve of IK(S) during exposure to LAP or SOR was shifted toward a less negative potential, with no change in the gating charge required to activate the current. LAP shortened the recovery from IK(S) deactivation. As rapid repetitive stimuli, the IK(S) amplitude decreased; however; the LAP-induced inhibition of IK(S) remained effective. LAP or SOR alone also suppressed inwardly rectifying K+ and voltage-gated Na+ current in neonatal rat ventricular myocytes. The inhibition of ionic currents during exposure to TKIs could be an important mechanism underlying changes in QTc intervals.

scholarly journals Single-Molecule Dynamics and Discrimination between Hydrophilic and Hydrophobic Amino Acids in Peptides, through Controllable, Stepwise Translocation across Nanopores

2018 ◽  
Author(s):  
Alina Asandei ◽  
Isabela S. Dragomir ◽  
Giovanni Di Muccio ◽  
Mauro Chinappi ◽  
Yoonkyung Park ◽  
...  
Keyword(s):  
Amino Acids ◽  
Single Molecule ◽  
Ionic Current ◽  
Ionic Currents ◽  
Alpha Hemolysin ◽  
Time Discrimination ◽  
Voltage Dependent ◽  
Hydrophobic Amino Acids ◽  
Molecular Brake ◽  
Oppositely Charged

In this work we demonstrate the proof-of-concept of real-time discrimination between patches of serine or isoleucine monomers in the primary structure of custom-engineered, macro-dipole-like peptides, at uni-molecular level. We employed single-molecule recordings to examine the ionic current through the α-hemolysin (α-HL) nanopore, when hydrophilic serine or hydrophobic isoleucine residues, flanked by segments of oppositely charged arginine and glutamic amino acids functioning as a voltage-dependent ‘molecular brake’ on the peptide, were driven at controllable rates across the nanopore. The observed differences in the ionic currents blockades through the nanopore, visible at time resolutions corresponding to peptide threading through the α-HL’s constriction region, was explained by a simple model of the volumes of electrolyte excluded by either amino acid species, as groups of three serine or isoleucine monomers transiently occupy the α-HL. To provide insights into the conditions ensuring optimal throughput of peptide readout through the nanopore, we probed the sidedness-dependence of peptide association to and dissociation from the electrically and geometrically asymmetric α-HL.

scholarly journals Deconvoluting and Quantifying the Real-time Fluxes and Ionic Currents of Various Species Using In Situ Electrochemical Quartz Crystal Microbalance Measurements

2021 ◽  
Author(s):  
Kai Zheng ◽  
Yongqiu Xian ◽  
Zifeng LIN
Keyword(s):  
Real Time ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Ionic Current ◽  
Ionic Currents ◽  
Electrochemical Quartz Crystal Microbalance ◽  
Cyclic Voltammograms ◽  
Supercapacitor Electrode ◽  
The Real ◽  
Porous Carbon Electrode

Electrochemical quartz crystal microbalance (EQCM) is a powerful technique to screen the gravimetric response of electrochemical electrodes. In this study, a straightforward mathematical method is proposed for extracting and deconvoluting the real-time fluxes and ionic currents of two species based on the EQCM measurement results. We creatively propose the concept of flux cyclic voltammograms (CVs) and ionic current CVs of various species and apply them to the real-time analyses of molecules/ions dynamics. For proof of concept, Ti3C2Tx MXene, a most studied two-dimensional metal carbide, is investigated as a supercapacitor electrode in a 1M H2SO4 electrolyte. The H2O and H+ flux CV plots are highly symmetrical, indicating reversible inserting/deserting species fluxes. The highest fluxes along with maximum hydration numbers are obtained at the peak current potential. This suggests the significant contribution of double-layer capacitance originates from the insertion of hydrated H+. The H+ CV with the ionic current induced by H+ flux overlaps the real CV, confirming that H+ is the only interactive ion for screening the electrode charge. Lastly, we also validate the proposed strategy using Ti3C2Tx MXene electrode in 1M KCl electrolyte and YP80 porous carbon electrode in 1 M LiCl electrolyte.

Bone as an ion exchange system: evidence for a link between mechanotransduction and metabolic needs

2002 ◽  
Vol 282 (4) ◽  
pp. E851-E864 ◽  
Author(s):  
A. Rubinacci ◽  
M. Covini ◽  
C. Bisogni ◽  
I. Villa ◽  
M. Galli ◽  
...  
Keyword(s):  
Current Density ◽  
Ex Vivo ◽  
Ionic Current ◽  
Extracellular Fluid ◽  
Ionic Currents ◽  
Dependent Manner ◽  
Metabolic Functions ◽  
Metatarsal Bones ◽  
Dose Dependent

To detect whether the mutual interaction occurring between the osteocytes-bone lining cells system (OBLCS) and the bone extracellular fluid (BECF) is affected by load through a modification of the BECF-extracellular fluid (ECF; systemic extracellular fluid) gradient, mice metatarsal bones immersed in ECF were subjected ex vivo to a 2-min cyclic axial load of different amplitudes and frequencies. The electric (ionic) currents at the bone surface were measured by a vibrating probe after having exposed BECF to ECF through a transcortical hole. The application of different loads and different frequencies increased the ionic current in a dose-dependent manner. The postload current density subsequently decayed following an exponential pattern. Postload increment's amplitude and decay were dependent on bone viability. Dummy and static loads did not induce current density modifications. Because BECF is perturbed by loading, it is conceivable that OBLCS tends to restore BECF preload conditions by controlling ion fluxes at the bone-plasma interface to fulfill metabolic needs. Because the electric current reflects the integrated activity of OBLCS, its evaluation in transgenic mice engineered to possess genetic lesions in channels or matrix constituents could be helpful in the characterization of the mechanical and metabolic functions of bone.

Characterization of Ionic Currents in Peptidergic Neurons from Eyestalks of Chinese Mitten Crab Eriocheir sinensis

2011 ◽  
Vol 108 ◽  
pp. 116-120
Author(s):  
Jin Sheng Sun ◽  
Li Ping Wang ◽  
Xu Yun Geng
Keyword(s):  
Ionic Current ◽  
Ionic Currents ◽  
Eriocheir Sinensis ◽  
Neurosecretory Cells ◽  
Transient Current ◽  
Peptidergic Neurons ◽  
Chinese Mitten Crab ◽  
Patch Clamp Technique ◽  
Outward Currents ◽  
Mitten Crab

The Whole-cell patch clamp technique was used to study the properties of voltage dependent ion channel expressed by the cultured types A、B、C neurosecretory cells dissociated from medulla terminalis X-organ (MTXO) of Chinese mitten crab Eriocheir sinensis 24-48 hours after plating. Under voltage clamp conditions, significantly inward currents were recorded from all three kinds of neurons, followed by large outward currents. When outward currents were suppressed with use of 3mmol/L 4-aminopyridine (4-AP) and 30mmol/L tetraethylammonium (TEA), a tetrodotoxin-sensitive Na+ current （INa） and a slow (time to peak current 6~8mS at +10mV), Cd2+-sensitive Ca2+ current (ICa) were resolved. INa was activated at potential-40mV and was maximal at-10mV. In TTX, ICa was activated at potential-30mV, was maximal at 10~20mV. In the presence of 1mol/L TTX and 0.5mmol/L Cd2+, a 4-AP-sensitive transient current and a slower-rising, TEA-sensitive current were recorded from a holding potential of-50mV. On the basis of electric feature and pharmacology, transient current was identified as IA, and late, slower-rising current as IK. IA and IK showed the same activation threshold of-30mV. In conclusion, no differences were observed on the properties and kinetics of ionic current among the three kinds of neurons. By comparison with those described in crab Cardisoma carnifex and crayfish Procambarus clarkia, there existed diversity of excitability in X-organ peptidergic neurons from different crustaceans.

scholarly journals Heterologous expression of BI Ca2+ channels in dysgenic skeletal muscle.

1994 ◽  
Vol 104 (5) ◽  
pp. 985-996 ◽  
Author(s):  
B A Adams ◽  
Y Mori ◽  
M S Kim ◽  
T Tanabe ◽  
K G Beam
Keyword(s):  
Skeletal Muscle ◽  
Time Constant ◽  
Ionic Current ◽  
Ionic Currents ◽  
Rabbit Brain ◽  
Charge Movement ◽  
Patch Clamp Technique ◽  
Open Probability ◽  
Whole Cell Patch Clamp ◽  
Ca2 Channels

We have examined the ability of BI (class A) Ca2+ channels, cloned from rabbit brain, to mediate excitation-contraction (E-C) coupling in skeletal muscle. Expression plasmids carrying cDNA encoding BI channels were microinjected into the nuclei of dysgenic mouse myotubes grown in primary culture. Ionic currents and intramembrane charge movements produced by the BI channels were recorded using the whole-cell patch-clamp technique. Injected myotubes expressed high densities of ionic BI Ca2+ channel current (average 31 pA/pF) but did not display spontaneous contractions, and only very rarely displayed evoked contractions. The expressed ionic current was pharmacologically distinguished from the endogenous L-type current of dysgenic skeletal muscle (Idys) by its insensitivity to the dihydropyridine antagonist (+)-PN 200-110. Peak BI Ca2+ currents activated with a time constant (tau a) of approximately 2 ms and inactivated with a time constant (tau h) of approximately 260 ms (20-23 degrees C). The time constant of inactivation (tau h) was not increased by substituting Ba2+ for Ca2+ as charge carrier, demonstrating that BI channels expressed in dysgenic myotubes do not undergo Ca(2+)-dependent inactivation. The average maximal Ca2+ conductance (Gmax) produced by the BI channels was quite large (approximately 534 S/F). In contrast, the average maximal charge movement (Qmax) produced in the same myotubes (approximately 2.7 nC/microF) was quite small, being barely larger than Qmax in control dysgenic myotubes (approximately 2.3 nC/microF). Thus, the ratio Gmax/Qmax for the BI channels was considerably higher than previously found for cardiac or skeletal muscle L-type Ca2+ channels expressed in the same system, indicating that neuronal BI Ca2+ channels exhibit a much higher open probability than these L-type Ca2+ channels.

scholarly journals Signal transmission through seawater for MHz frequencies and medium distances (0–30 m) using ionic current waves

2019 ◽  
Vol 36 (3) ◽  
pp. 53-61
Author(s):  
Emeritus J Lucas
Keyword(s):  
Signal Transmission ◽  
Full Range ◽  
Ionic Current ◽  
Electrical Energy ◽  
Ionic Currents ◽  
Signal Propagation ◽  
Signal Loss ◽  
Deep Seawater ◽  
Sonar Systems ◽  
Submarine Communications

Electromagnetic (EM) signals can only be transmitted through seawater for short distances (<1 m) for frequencies (>1 MHz). Therefore a new technique, the ionic current wave (ICW), has been developed for signal propagation at MHz frequency. This technique uses the conduction current produced in seawater as a result of thermal ionisation releasing H+ and OH– ions. A small voltage (<1.5 V pk) is applied between two metal electrodes submerged in the seawater to avoid ionisation by the input electrical energy.<br/> A detailed theoretical analysis of the ICW process has shown that ionic currents can be transmitted at MHz frequency over distances of 10 m with low signal loss per decade. For longer propagation distances of 100 m the theory predicts a signal loss of –20 dB per decade.<br/> Propagation experiments have been carried out in Liverpool dock seawater for distances of 2 m–28 m between parallel 0.5 m × 0.3 m electrodes placed vertically in the seawater at a depth of 2 m. Signal frequencies within the range of 1 MHz–8 MHz have been investigated. In each experiment the received propa gated signal power was approximately –67 dBm (well above the dock electrical noise of –140 dBm) and only showed a small power loss over the full range of propagation.<br/> The ICW system will be able to measure longer propagation distances in deep seawater conditions suitable for ship and submarine communications. Its performance is comparable to that of sonar systems.

scholarly journals DNA sequence-dependent ionic currents in ultra-small solid-state nanopores

Nanoscale ◽  
2016 ◽  
Vol 8 (18) ◽  
pp. 9600-9613 ◽  
Author(s):  
Jeffrey Comer ◽  
Aleksei Aksimentiev
Keyword(s):  
Solid State ◽  
Dna Sequence ◽  
Ionic Current ◽  
Ionic Currents ◽  
Atomic Resolution ◽  
Sequence Dependent ◽  
Dna Strand

Atomic resolution simulations elucidate the effect of DNA sequence and conformation on the ionic current blockades produced by the presence of a DNA strand in an ultra-small solid-state nanopore.

Transmural action potential and ionic current remodeling in ventricles of failing canine hearts

2002 ◽  
Vol 283 (3) ◽  
pp. H1031-H1041 ◽  
Author(s):  
Gui-Rong Li ◽  
Chu-Pak Lau ◽  
Anique Ducharme ◽  
Jean-Claude Tardif ◽  
Stanley Nattel
Keyword(s):  
Left Ventricle ◽  
Action Potential ◽  
Action Potentials ◽  
Slow Component ◽  
Ionic Current ◽  
Ionic Currents ◽  
Cell Types ◽  
Delayed Rectifier ◽  
Cardiac Repolarization ◽  
Early Afterdepolarizations

Heart failure (HF) produces important alterations in currents underlying cardiac repolarization, but the transmural distribution of such changes is unknown. We therefore recorded action potentials and ionic currents in cells isolated from the endocardium, midmyocardium, and epicardium of the left ventricle from dogs with and without tachypacing-induced HF. HF greatly increased action potential duration (APD) but attenuated APD heterogeneity in the three regions. Early afterdepolarizations (EADs) were observed in all cell types of failing hearts but not in controls. Inward rectifier K+ current ( I K1) was homogeneously reduced by ∼41% (at −60 mV) in the three cell types. Transient outward K+ current ( I to1) was decreased by 43–45% at +30 mV, and the slow component of the delayed rectifier K+ current ( I Ks) was significantly downregulated by 57%, 49%, and 58%, respectively, in epicardial, midmyocardial, and endocardial cells, whereas the rapid component of the delayed rectifier K+ current was not altered. The results indicate that HF remodels electrophysiology in all layers of the left ventricle, and the downregulation of I K1, I to1, and I Ks increases APD and favors occurrence of EADs.

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