The long-lasting cardiac action potentials are related to pressure generation in the heart

2021 ◽  
Author(s):  
José Guilherme Chaui-Berlinck ◽  
Vitor Rodrigues da Silva
Keyword(s):  
Action Potentials ◽  
Cardiac Action

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>

The influence of fibroblast co-culture and 3D structures on cardiac action potentials of human stem cell-derived cardiomyocytes

2018 ◽  
Vol 93 ◽  
pp. 169
Author(s):  
Maria P. Hortigon-Vinagre ◽  
Victor Zamora ◽  
Gary Gintant ◽  
Jonathon Green ◽  
Francis L. Burton ◽  
...  
Keyword(s):  
Stem Cell ◽  
Action Potentials ◽  
Human Stem Cell ◽  
3D Structures ◽  
Cardiac Action

scholarly journals KCNE1 and KCNE3 modulate KCNQ1 channels by affecting different gating transitions

2017 ◽  
Vol 114 (35) ◽  
pp. E7367-E7376 ◽  
Author(s):  
Rene Barro-Soria ◽  
Rosamary Ramentol ◽  
Sara I. Liin ◽  
Marta E. Perez ◽  
Robert S. Kass ◽  
...  
Keyword(s):  
Action Potentials ◽  
Potassium Current ◽  
Voltage Sensor ◽  
Α Subunit ◽  
Voltage Range ◽  
Gate Opening ◽  
Cardiac Action ◽  
Repolarization Phase ◽  
Voltage Dependent ◽  
Salt Secretion

KCNE β-subunits assemble with and modulate the properties of voltage-gated K+ channels. In the heart, KCNE1 associates with the α-subunit KCNQ1 to generate the slowly activating, voltage-dependent potassium current (IKs) in the heart that controls the repolarization phase of cardiac action potentials. By contrast, in epithelial cells from the colon, stomach, and kidney, KCNE3 coassembles with KCNQ1 to form K+ channels that are voltage-independent K+ channels in the physiological voltage range and important for controlling water and salt secretion and absorption. How KCNE1 and KCNE3 subunits modify KCNQ1 channel gating so differently is largely unknown. Here, we use voltage clamp fluorometry to determine how KCNE1 and KCNE3 affect the voltage sensor and the gate of KCNQ1. By separating S4 movement and gate opening by mutations or phosphatidylinositol 4,5-bisphosphate depletion, we show that KCNE1 affects both the S4 movement and the gate, whereas KCNE3 affects the S4 movement and only affects the gate in KCNQ1 if an intact S4-to-gate coupling is present. Further, we show that a triple mutation in the middle of the transmembrane (TM) segment of KCNE3 introduces KCNE1-like effects on the second S4 movement and the gate. In addition, we show that differences in two residues at the external end of the KCNE TM segments underlie differences in the effects of the different KCNEs on the first S4 movement and the voltage sensor-to-gate coupling.

A note on the phase-plane technique representation of cardiac action potentials

1976 ◽  
Vol 10 (1) ◽  
pp. 136-138
Author(s):  
E. L. DE BEER ◽  
H. B. K. BOOM ◽  
H. C. SCHAMHARDT
Keyword(s):  
Action Potentials ◽  
Phase Plane ◽  
Cardiac Action ◽  
Plane Technique

Abstract 17189: Reprogramming of Fibroblasts Into Cardiac Progenitor Cells Using Crispr Activation System

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_1) ◽  
Author(s):  
Lin Jiang ◽  
Jialiang Liang ◽  
Wei Huang ◽  
Christian Paul ◽  
Yigang Wang
Keyword(s):  
Action Potentials ◽  
Differentiation Potential ◽  
Lineage Differentiation ◽  
Cardiac Action ◽  
Reporter Mice ◽  
Gfp Reporter ◽  
Control Virus ◽  
Cardiac Lineage ◽  
Tail Tip ◽  
Crispr Activation

Background and Objective: CRISPR tools that allow for precise manipulation of individual loci have not been used in generation of i nduced c ardiac p rogenitor c ells ( iCPC s). This study was designed to determine the feasibility and effectiveness of reprogramming fibroblasts into iCPC using CRISPR activation (CRISPRa) system. Methods: Tail-tip fibroblasts (TTFs) were isolated from Nkx2-5 cardiac enhancer GFP reporter mice. A gRNA pool targeting 17 progenitor genes was synthesized and transduced with dCas9-VP64 lentivirus into TTFs ( Fig.1A ). The phenotype of iCPCs was then characterized by immunostaining and FACS of progenitor markers. Finally, the cardiac-lineage differentiation potential of iCPCs was determined by immunostaining and electrophysiological assay under defined induction mediums. Results: iCPCs with GFP expression were formed in TTFs after transduction of CRISPRa targeting Isl1 , Gata4 , Baf60c , Tbx5 and Nkx2-5 (Fig.1B), while GFP was not activated by control virus. Cardiac progenitor markers were activated in iCPCs as shown by immunostaining (Fig.1C). The generation efficiency of Flk1-postive iCPCs induced by CRISPRa was ~60% as showed by FACS. iCPCs can be differentiated into cardiomyocytes as identified by immunostaining of cardiac-specific markers (Fig.1D). The iCPC-derived cardiomyocytes displayed spontaneous beating and showed cardiac action potentials (Fig.1E). Conclusion: The CRISPRa system is an efficient and specific way to generate iCPCs, which could provide a novel source of cells for cardiac regenerative medicine.

The generation of electric currents in cardiac fibers by Na/Ca exchange

1979 ◽  
Vol 236 (3) ◽  
pp. C103-C110 ◽  
Author(s):  
L. J. Mullins
Keyword(s):  
Membrane Potential ◽  
Duty Cycle ◽  
Action Potentials ◽  
Reversal Potential ◽  
Resting Membrane Potential ◽  
Electrochemical Gradient ◽  
Ca Current ◽  
Cardiac Action ◽  
Cardiac Fiber ◽  
Cardiac Fibers

The presence of a detectable Ca current during the excitation of a cardiac fiber implies that the Ca lost during the resting interval of the duty cycle must also be detectable. Ca outward movement appears to be effected by Na/Ca exchange when more Na enters than Ca leaves per cycle, thus making the mechanism electrogenic. Since Na/Ca exchange can move Ca either inward or outward depending on the direction of the electrochemical gradient for Na, a potential exists where there is no electric current generated by the Na/Ca exchange mechanism, i.e., a reversal potential ER. Cardiac fibers appear to have a reversal potential that is about midway between their resting membrane potential and their plateau. Carrier currents both inward and outward are therefore generated during cardiac action potentials. The implications of the conditions stated above are explored.

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