The Effects of Fast Sodium Current Upon Action Potential of Cardiac Cells Exposed to External Electric Fields

2007 ◽  
Author(s):  
Anying Zhang ◽  
Qing Yan ◽  
Xiaofeng Pang
Keyword(s):  
Action Potential ◽  
Electric Fields ◽  
Sodium Current ◽  
Cardiac Cells ◽  
External Electric Fields ◽  
Fast Sodium Current

Effects of uniform electric fields on intracellular calcium transients in single cardiac cells

2002 ◽  
Vol 282 (1) ◽  
pp. H72-H79 ◽  
Author(s):  
Vinod Sharma ◽  
Leslie Tung
Keyword(s):  
Cell Membrane ◽  
Guinea Pig ◽  
Action Potential ◽  
Intracellular Calcium ◽  
Electric Fields ◽  
Cardiac Cells ◽  
Calcium Transients ◽  
Uniform Field ◽  
Field Stimulation ◽  
Mapping System

Although intracellular calcium ([Ca2+]i) transients in cardiac cells have been well studied in the uniformly polarized cell membrane, how these transients are modified during field stimulation when the cell membrane is nonuniformly polarized has not been investigated. In this study we characterized the effects of uniform field stimuli on [Ca2+]i transients in isolated guinea pig cardiac cells. Single guinea pig cells were enzymatically isolated, loaded with the [Ca2+]i fluorescent indicator fluo-3, and stimulated along their longitudinal axes with S1 or S1-S2 (S1-S2 = 50 ms) pulses. The fluorescence signals were recorded simultaneously from up to 12 sites along the cell length using a multisite mapping system. S1 pulse, applied during the resting phase of the action potential, induced [Ca2+]itransients that had an earlier onset at the anodal-facing end, suggesting that [Ca2+]i gradients (∇[Ca2+]i) develop during the rising phase of the [Ca2+]i transients. With the assumption that the peak change in [Ca2+]i is 980 nM, ∇[Ca2+]i was estimated to be ∼3.4 nM/μm in the anodal half of the cell for a nominal 10 V/cm field and negligible in the cathodal half. The S2 pulse that was applied during the plateau of the action potential also perturbed the [Ca2+]i transients and produced [Ca2+]i gradients directed from the center to either end of the cell. Mean ∇[Ca2+]i in the anodal half of the cell (∼4.2 nM/μm) was found to be statistically higher than in the cathodal half (∼2.8 nM/μm).

Separation of Na-Ca exchange and transient inward currents in heart cells

1987 ◽  
Vol 253 (5) ◽  
pp. H1330-H1333
Author(s):  
Y. Shimoni ◽  
W. Giles
Keyword(s):  
Sodium Current ◽  
Single Cells ◽  
Cardiac Cells ◽  
Slow Inward Current ◽  
Heart Cells ◽  
Inward Current ◽  
Inward Currents ◽  
Isolated Cardiac Cells ◽  
Fast Sodium Current ◽  
External K

Enzymatically dispersed single cells from rabbit ventricle were voltage clamped using the suction pipette method to investigate whether in isolated cardiac cells a recently described slow inward current (IEX) due to the electrogenic Na+-dependent Ca2+ extrusion also underlies a transient inward current (ITI), which can trigger certain cardiac arrhythmias. The cells were held at -40 mV to inactivate the fast sodium current. After depolarizing pulses (to 0 or +10 mV for 50 to 200 ms), slow inward "tail" currents were consistently recorded. Previous results indicate that this tail current IEX is generated by the Na+-Ca2+ exchanger. After loading the cells with Ca2+ by blocking the Na+-K+ pump [either with strophanthidin (10(-5) M) treatment or by reducing external K+ to 1 mM or less], ITIS appeared. These were usually spontaneous but occasionally were time locked to the clamp pulses. It was possible to separate IEX and ITI by a variety of methods. These include the following. 1) Different stimulation protocols; repolarizing to more negative potentials augmented IEX and decreased or eliminated ITI. Increasing the rate of stimulation diminished IEX and increased ITI. 2) Pharmacological methods; adding BaCl2 (0.5-2.0 mM) or caffeine (5-10 mM) decreased IEX but abolished ITI. The findings suggest that different mechanisms regulate these two currents.

scholarly journals Emulsions in external electric fields

2021 ◽  
pp. 102455
Author(s):  
Johan Sjöblom ◽  
Sameer Mhatre ◽  
Sébastien Simon ◽  
Roar Skartlien ◽  
Geir Sørland
Keyword(s):  
Electric Fields ◽  
External Electric Fields

scholarly journals Vacancy tuned thermoelectric properties and high spin filtering performance in graphene/silicene heterostructures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zainab Gholami ◽  
Farhad Khoeini
Keyword(s):  
Electric Fields ◽  
High Spin ◽  
High Efficiency ◽  
Practical Applications ◽  
External Electric Fields ◽  
Ferromagnetic Exchange ◽  
High Spin Polarization ◽  
Filtering Effect ◽  
Spin Switching ◽  
Spin Filtering

AbstractThe main contribution of this paper is to study the spin caloritronic effects in defected graphene/silicene nanoribbon (GSNR) junctions. Each step-like GSNR is subjected to the ferromagnetic exchange and local external electric fields, and their responses are determined using the nonequilibrium Green’s function (NEGF) approach. To further study the thermoelectric (TE) properties of the GSNRs, three defect arrangements of divacancies (DVs) are also considered for a larger system, and their responses are re-evaluated. The results demonstrate that the defected GSNRs with the DVs can provide an almost perfect thermal spin filtering effect (SFE), and spin switching. A negative differential thermoelectric resistance (NDTR) effect and high spin polarization efficiency (SPE) larger than 99.99% are obtained. The system with the DV defects can show a large spin-dependent Seebeck coefficient, equal to Ss ⁓ 1.2 mV/K, which is relatively large and acceptable. Appropriate thermal and electronic properties of the GSNRs can also be obtained by tuning up the DV orientation in the device region. Accordingly, the step-like GSNRs can be employed to produce high efficiency spin caloritronic devices with various features in practical applications.

scholarly journals Cisplatin under oriented external electric fields: A deeper insight into electrochemotherapy at the molecular level

2020 ◽  
Author(s):  
Li Zhang ◽  
Ya‐Ling Ye ◽  
Xiao‐Ling Zhang ◽  
Xiang‐Hui Li ◽  
Qiao‐Hong Chen ◽  
...  
Keyword(s):  
Electric Fields ◽  
Molecular Level ◽  
External Electric Fields ◽  
Insight Into

An experimental and simulation study on the self-assembly of colloidal cubes in external electric fields

Soft Matter ◽  
2014 ◽  
Vol 10 (45) ◽  
pp. 9110-9119 ◽  
Author(s):  
Hanumantha Rao Vutukuri ◽  
Frank Smallenburg ◽  
Stéphane Badaire ◽  
Arnout Imhof ◽  
Marjolein Dijkstra ◽  
...  
Keyword(s):  
Electric Fields ◽  
Simulation Study ◽  
Self Assembly ◽  
The Self ◽  
External Electric Fields
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