scholarly journals High purity human-induced pluripotent stem cell-derived cardiomyocytes: electrophysiological properties of action potentials and ionic currents

2011 ◽  
Vol 301 (5) ◽  
pp. H2006-H2017 ◽  
Author(s):  
Junyi Ma ◽  
Liang Guo ◽  
Steve J. Fiene ◽  
Blake D. Anson ◽  
James A. Thomson ◽  
...  
Keyword(s):  
Cardiac Myocytes ◽  
High Purity ◽  
Action Potentials ◽  
Ionic Currents ◽  
Delayed Rectifier ◽  
Cardiovascular Research ◽  
Peak Voltage ◽  
Electrophysiological Properties ◽  
Induced Pluripotent ◽  
Multiple Drugs

Human-induced pluripotent stem cells (hiPSCs) can differentiate into functional cardiomyocytes; however, the electrophysiological properties of hiPSC-derived cardiomyocytes have yet to be fully characterized. We performed detailed electrophysiological characterization of highly pure hiPSC-derived cardiomyocytes. Action potentials (APs) were recorded from spontaneously beating cardiomyocytes using a perforated patch method and had atrial-, nodal-, and ventricular-like properties. Ventricular-like APs were more common and had maximum diastolic potentials close to those of human cardiac myocytes, AP durations were within the range of the normal human electrocardiographic QT interval, and APs showed expected sensitivity to multiple drugs (tetrodotoxin, nifedipine, and E4031). Early afterdepolarizations (EADs) were induced with E4031 and were bradycardia dependent, and EAD peak voltage varied inversely with the EAD take-off potential. Gating properties of seven ionic currents were studied including sodium ( INa), L-type calcium ( ICa), hyperpolarization-activated pacemaker ( If), transient outward potassium ( Ito), inward rectifier potassium ( IK1), and the rapidly and slowly activating components of delayed rectifier potassium ( IKr and IKs, respectively) current. The high purity and large cell numbers also enabled automated patch-clamp analysis. We conclude that these hiPSC-derived cardiomyocytes have ionic currents and channel gating properties underlying their APs and EADs that are quantitatively similar to those reported for human cardiac myocytes. These hiPSC-derived cardiomyocytes have the added advantage that they can be used in high-throughput assays, and they have the potential to impact multiple areas of cardiovascular research and therapeutic applications.

Ionic Currents Underlying Fast Action Potentials in the Obliquely Striated Muscle Cells of the Octopus Arm

2002 ◽  
Vol 88 (6) ◽  
pp. 3386-3397 ◽  
Author(s):  
Dan Rokni ◽  
Binyamin Hochner
Keyword(s):  
Time Constant ◽  
Action Potentials ◽  
Striated Muscle ◽  
Muscle Cells ◽  
Ionic Currents ◽  
Delayed Rectifier ◽  
Inactivation Kinetics ◽  
Activation Kinetics ◽  
Voltage Dependent ◽  
Neuromuscular Systems

The octopus arm provides a unique model for neuromuscular systems of flexible appendages. We previously reported the electrical compactness of the arm muscle cells and their rich excitable properties ranging from fast oscillations to overshooting action potentials. Here we characterize the voltage-activated ionic currents in the muscle cell membrane. We found three depolarization-activated ionic currents: 1) a high-voltage-activated L-type Ca2+ current, which began activating at approximately −35 mV, was eliminated when Ca2+ was substituted by Mg2+, was blocked by nifedipine, and showed Ca2+-dependent inactivation. This current had very rapid activation kinetics (peaked within milliseconds) and slow inactivation kinetics (τ in the order of 50 ms). 2) A delayed rectifier K+ current that was totally blocked by 10 mM TEA and partially blocked by 10 mM 4-aminopyridine (4AP). This current exhibited relatively slow activation kinetics (τ in the order of 15 ms) and inactivated only partially with a time constant of ∼150 ms. And 3) a transient A-type K+ current that was totally blocked by 10 mM 4AP and was partially blocked by 10 mM TEA. This current exhibited very fast activation kinetics (peaked within milliseconds) and inactivated with a time constant in the order of 60 ms. Inactivation of the A-type current was almost complete at −40 mV. No voltage-dependent Na+ current was found in these cells. The octopus arm muscle cells generate fast (∼3 ms) overshooting spikes in physiological conditions that are carried by a slowly inactivating L-type Ca2+ current.

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.

Sex-based transmural differences in cardiac repolarization and ionic-current properties in canine left ventricles

2006 ◽  
Vol 291 (2) ◽  
pp. H570-H580 ◽  
Author(s):  
Ling Xiao ◽  
Liming Zhang ◽  
Wei Han ◽  
Zhiguo Wang ◽  
Stanley Nattel
Keyword(s):  
Sex Differences ◽  
Action Potentials ◽  
Ionic Current ◽  
Ionic Currents ◽  
Left Ventricular ◽  
Delayed Rectifier ◽  
Cardiac Repolarization ◽  
Qt Intervals ◽  
Whole Cell Patch Clamp ◽  
Ventricular Cells

The female sex is associated with longer electrocardiographic QT intervals and increased proarrhythmic risks of QT-prolonging drugs. This study examined the hypothesis that sex differences in repolarization may be associated with differential transmural ion-current distribution. Whole cell patch-clamp and current-clamp were used to study ionic currents and action potentials (APs) in isolated canine left ventricular cells from epicardium, midmyocardium, and endocardium. No sex differences in AP duration (APD) were found in cells from epicardium versus endocardium. In midmyocardium, APD was significantly longer in female dogs (e.g., at 1 Hz, female vs. male: 288 ± 21 vs. 237 ± 8 ms; P < 0.05), resulting in greater transmural APD heterogeneity in females. No sex differences in inward rectifier K+ current ( IK1) were observed. Transient outward K+ current ( Ito) densities in epicardium and midmyocardium also showed no sex differences. In endocardium, female dogs had significantly smaller Ito (e.g., at +30 mV, female vs. male: 2.5 ± 0.2 vs. 3.5 ± 0.3 pA/pF; P < 0.05). Rapid delayed-rectifier K+ current ( IKr) density and activation voltage-dependence showed no sex differences. Female dogs had significantly larger slow delayed-rectifier K+ current ( IKs) in epicardium and endocardium (e.g., at +40 mV; tail densities, female vs. male; epicardium: 1.3 ± 0.1 vs. 0.8 ± 0.1 pA/pF; P < 0.001; endocardium: 1.2 ± 0.1 vs. 0.7 ± 0.1 pA/pF; P < 0.05), but there were no sex differences in midmyocardial IKs. Female dogs had larger L-type Ca2+ current ( ICa,L) densities in all layers than male dogs (e.g., at −20 mV, female vs. male, epicardium: −4.2 ± 0.4 vs. −3.2 ± 0.2 pA/pF; midmyocardium: −4.5 ± 0.5 vs. −3.3 ± 0.3 pA/pF; endocarium: −4.5 ± 0.4 vs. −3.2 ± 0.3 pA/pF; P < 0.05 for each). We conclude that there are sex-based transmural differences in ionic currents that may underlie sex differences in transmural cardiac repolarization.

Abstract P092: Simplified Monolayer Differentiation of Human-Induced Pluripotent Stem Cells to Functional Cardiac Myocytes

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Jennifer K Lang ◽  
Stanley Fernandez ◽  
Thomas Cimato
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cardiac Myocytes ◽  
Pluripotent Stem Cells ◽  
Action Potentials ◽  
Cardiac Myocyte ◽  
Human Ipscs ◽  
Myocyte Differentiation ◽  
Induced Pluripotent

Background: Human induced pluripotent stem cells (hiPSCs) are an important model for cardiovascular research, drug discovery, and translational research applications. Commonly used methods to direct iPSCs to cardiac myocytes can be technically demanding. Prior studies have shown that both VEGF and endothelial cells promote differentiation of stem cells to cardiac myocytes. Furthermore, DMEM/F12 with 10% fetal calf serum (DMEM-FCS) has been shown to induce cardiac myocytes in an embryoid body (EB) system. The objective of this study was to determine if differentiation of hiPSCs using conditions that support endothelial cell differentiation would promote cardiac myocyte colony formation. Methods: Two hiPSC lines derived using non-genome integrating methods were maintained on Matrigel-coated surfaces under serum free conditions in mTeSR1 medium. We performed a comparison of monolayer myocyte differentiation efficiency using DMEM-FCS and endothelial cell medium (EC). Cells were maintained in iPSC medium (mTeSR1) as a negative control. The number of beating colonies derived under each growth condition was determined using phase microscopy at 4 weeks. Cardiac myocyte commitment was characterized using an α-MHC-GFP reporter vector and electrophysiologic action potentials on isolated beating colonies. Results: Differentiation of human iPSCs in EC medium induced substantial numbers of beating colonies 4 weeks after differentiation (2.29 ± 0.3 beating colonies/cm2 culture area, n=42). Unlike EB models of myocyte differentiation, no beating clusters were observed in our monolayer system with DMEM-FCS medium (n=14) (p<0.01). As expected, mTESR1 (n=12) did not induce any cardiac myocytes. All beating cell colonies expressed GFP driven by the cardiac specific α-MHC promoter. Electrophysiological studies confirmed the presence of action potentials with ventricular phenotypes. Conclusions: Differentiation of human iPSCs under monolayer conditions that support endothelial cells facilitates efficient induction of functional human cardiac myocytes. Our findings simplify the differentiation of iPSCs to cardiac myocytes, making research with human iPSCs more accessible to a broad range of cardiovascular investigators.

Properties of sodium and potassium currents of cultured adult human atrial myocytes

1996 ◽  
Vol 270 (5) ◽  
pp. H1676-H1686 ◽  
Author(s):  
J. Feng ◽  
G. R. Li ◽  
B. Fermini ◽  
S. Nattel
Keyword(s):  
Primary Culture ◽  
Molecular Mechanisms ◽  
Voltage Dependence ◽  
Phenotypic Expression ◽  
Ionic Currents ◽  
Delayed Rectifier ◽  
Atrial Myocytes ◽  
Qualitative Properties ◽  
Human Atrial Myocytes ◽  
Electrophysiological Properties

Cultured cell systems are valuable for the study of regulation of phenotypic expression, but little is known about the electrophysiological properties of human cardiac tissues in culture. The present studies were designed to determine the feasibility of maintaining human atrial myocytes in primary culture and to assess changes in Na+ (INa) and K+ (Ito, transient outward, and Ikur, ultra-rapid delayed rectifier) currents. Within 24 h of culture, cells assumed an avoid shape, which they maintained for up to 7 days. The voltage dependence, kinetics, and density of INa were unchanged in culture. The activation properties of Ito (kinetics and voltage dependence) were not altered, but Ito density (current normalized to cell capacitance) was reduced and inactivation properties were altered (negative shift in voltage dependence and slowed kinetics) in cultured compared with fresh cells. The absolute current amplitude, kinetics, voltage dependence, and 4-aminopyridine sensitivity of IKur were unchanged, but current density was increased. All changes in ionic currents occurred within 24 h of culture and remained stable for the next 4 days. We conclude that human atrial myocytes can be maintained in primary culture, that the qualitative properties of INa, Ito, and IKur remain constant but that some quantitative changes occur, and that cultured human atrial myocytes may be valuable for studies of the molecular mechanisms and regulation of cardiac channel function in humans.

scholarly journals Functional ion channels in mouse cardiac c-kit+ cells

2010 ◽  
Vol 298 (5) ◽  
pp. C1109-C1117 ◽  
Author(s):  
Yi Han ◽  
Jia-Dao Chen ◽  
Zu-Mei Liu ◽  
Yuan Zhou ◽  
Jia-Hong Xia ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Ion Channels ◽  
Ion Channel ◽  
Ionic Currents ◽  
Delayed Rectifier ◽  
Rt Pcr ◽  
Electrophysiological Properties ◽  
Cell Progression ◽  
A Cell ◽  
Channel Currents

Cardiac c-kit+ cells are generally believed to be the major population of stem/progenitor cells in the heart and can be used as a cell source for cardiomyoplasty; however, the cellular electrophysiological properties are not understood in this type of cells. The present study was designed to investigate functional ion channels in undifferentiated mouse cardiac c-kit+ cells using approaches of whole cell patch voltage clamp, RT-PCR, and cell proliferation assay. It was found that three types of ionic currents were present in mouse cardiac c-kit+ cells, including a delayed rectifier K+ current (IKDR) inhibited by 4-aminopyridine (4-AP), an inward rectifier K+ current ( IKir) decreased by Ba2+, and a volume-sensitive chloride current ( ICl.vol) inhibited by 5-nitro-1-(3-phenylpropylamino) benzoic acid (NPPB). RT-PCR revealed that the corresponding ion channel genes, Kv1.1, Kv1.2, and Kv1.6 (for IKDR), Kir.1.1, Kir2.1, and Kir2.2 (likely responsible for IKir), and Clcn3 (for ICl.vol), were significant in mouse cardiac c-kit+ cells. The inhibition of ICl.vol with NPPB and niflumic acid, but not IKDR with 4-AP and tetraethylammonium, reduced cell proliferation and accumulated the cell progression at G0/G1 phase in mouse cardiac c-kit+ cells. Our results demonstrate that three types of functional ion channel currents (i.e., IKDR, IKir, and ICl.vol) are present in mouse cardiac c-kit+ cells, and ICl.vol participates in regulating cell proliferation.

scholarly journals Phorbol ester and endothelin-1 alter functional expression of Na+/Ca2+ exchange, K+, and Ca2+ currents in cultured neonatal rat myocytes

2011 ◽  
Vol 300 (2) ◽  
pp. H617-H626 ◽  
Author(s):  
José L. Puglisi ◽  
Weilong Yuan ◽  
Valeriy Timofeyev ◽  
Richard E. Myers ◽  
Nipavan Chiamvimonvat ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ventricular Myocytes ◽  
Ionic Currents ◽  
Functional Expression ◽  
Neonatal Rat ◽  
Delayed Rectifier ◽  
Electrophysiological Properties ◽  
Endothelin 1 ◽  
Cellular Hypertrophy ◽  
Myocyte Function

Endothelin-1 (ET-1) and activation of protein kinase C (PKC) have been implicated in alterations of myocyte function in cardiac hypertrophy and heart failure. Changes in cellular Ca2+ handling and electrophysiological properties also occur in these states and may contribute to mechanical dysfunction and arrhythmias. While ET-1 or PKC stimulation induces cellular hypertrophy in cultured neonatal rat ventricular myocytes (NRVMs), a system widely used in studies of hypertrophic signaling, there is little data about electrophysiological changes. Here we studied the effects of ET-1 (100 nM) or the PKC activator phorbol 12-myristate 13-acetate (PMA, 1 μM) on ionic currents in NRVMs. The acute effects of PMA or ET-1 (≤30 min) were small or insignificant. However, PMA or ET-1 exposure for 48–72 h increased cell capacitance by 100 or 25%, respectively, indicating cellular hypertrophy. ET-1 also slightly increased Ca2+ current density (T and L type). Na+/Ca2+ exchange current was increased by chronic pretreatment with either PMA or ET-1. In contrast, transient outward and delayed rectifier K+ currents were strongly downregulated by PMA or ET-1 pretreatment. Inward rectifier K+ current tended toward a decrease at larger negative potential, but time-independent outward K+ current was unaltered by either treatment. The enhanced inward and reduced outward currents also result in action potential prolongation after PMA or ET-1 pretreatment. We conclude that chronic PMA or ET-1 exposure in cultured NRVMs causes altered functional expression of cardiac ion currents, which mimic electrophysiological changes seen in whole animal and human hypertrophy and heart failure.

New Molecular Scaffolds for Fluorescent Voltage Indicators

2018 ◽  
Author(s):  
Steven Boggess ◽  
Shivaani Gandhi ◽  
Brian Siemons ◽  
Nathaniel Huebsch ◽  
Kevin Healy ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Action Potentials ◽  
Induced Pluripotent Stem Cell ◽  
Molecular Wire ◽  
Voltage Sensing ◽  
Design Synthesis ◽  
Cardiac Action ◽  
Action Potential Waveform ◽  
Induced Pluripotent ◽  
Voltage Sensing Domain

<div> <p>The ability to non-invasively monitor membrane potential dynamics in excitable cells like neurons and cardiomyocytes promises to revolutionize our understanding of the physiology and pathology of the brain and heart. Here, we report the design, synthesis, and application of a new class of fluorescent voltage indicator that makes use of a fluorene-based molecular wire as a voltage sensing domain to provide fast and sensitive measurements of membrane potential in both mammalian neurons and human-derived cardiomyocytes. We show that the best of the new probes, fluorene VoltageFluor 2 (fVF 2) readily reports on action potentials in mammalian neurons, detects perturbations to cardiac action potential waveform in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes, shows a substantial decrease in phototoxicity compared to existing molecular wire-based indicators, and can monitor cardiac action potentials for extended periods of time. Together, our results demonstrate the generalizability of a molecular wire approach to voltage sensing and highlights the utility of fVF 2 for interrogating membrane potential dynamics.</p> </div>

scholarly journals The electrophysiological effects of cannabidiol on action potentials and transmembrane potassium currents in rabbit and dog cardiac ventricular preparations

2021 ◽  
Author(s):  
Leila Topal ◽  
Muhammad Naveed ◽  
Péter Orvos ◽  
Bence Pászti ◽  
János Prorok ◽  
...  
Keyword(s):  
Side Effects ◽  
Action Potentials ◽  
Oral Intake ◽  
Potassium Currents ◽  
Delayed Rectifier ◽  
Cardiac Repolarization ◽  
Cardiovascular Side Effects ◽  
Channel Inhibition ◽  
Repolarization Reserve ◽  
Electrophysiological Effects

AbstractCannabis use is associated with known cardiovascular side effects such as cardiac arrhythmias or even sudden cardiac death. The mechanisms behind these adverse effects are unknown. The aim of the present work was to study the cellular cardiac electrophysiological effects of cannabidiol (CBD) on action potentials and several transmembrane potassium currents, such as the rapid (IKr) and slow (IKs) delayed rectifier, the transient outward (Ito) and inward rectifier (IK1) potassium currents in rabbit and dog cardiac preparations. CBD increased action potential duration (APD) significantly in both rabbit (from 211.7 ± 11.2. to 224.6 ± 11.4 ms, n = 8) and dog (from 215.2 ± 9.0 to 231.7 ± 4.7 ms, n = 6) ventricular papillary muscle at 5 µM concentration. CBD decreased IKr, IKs and Ito (only in dog) significantly with corresponding estimated EC50 values of 4.9, 3.1 and 5 µM, respectively, without changing IK1. Although the EC50 value of CBD was found to be higher than literary Cmax values after CBD smoking and oral intake, our results raise the possibility that potassium channel inhibition by lengthening cardiac repolarization might have a role in the possible proarrhythmic side effects of cannabinoids in situations where CBD metabolism and/or the repolarization reserve is impaired.

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