نتایج جستجو برای: repolarization

تعداد نتایج: 5285  

Journal: :Circulation research 1999
U C Hoppe D C Johns E Marbán B O'Rourke

To investigate the still-undetermined role of the Ca2+-independent transient outward current (Ito1) on repolarization of the cardiac action potential, we used cell fusion to introduce Ito1 into guinea pig cardiomyocytes, which normally lack this current. This technique enables the rapid delivery of premade functional ion channels to cardiomyocytes within hours of isolation, thus eliminating the...

Journal: :The Journal of General Physiology 1977
G E Kirsch R A Nichols S Nakajima

Tetanic stimulation of skeletal muscle fibers elicits a train of spikes followed by a long-lasting depolarization called the late after-potential (LAP). We have conducted experiments to determine the origin of the LAP. Isolated single muscle fibers were treated with a high potassium solution (5 mM or 10 mM K) followed by a sudden reduction of potassium concentration to 2.5 mM. This procedure pr...

Journal: :Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology 2006
Fiona E Smith Philip Langley Peter van Leeuwen Birgit Hailer Lutz Trahms Uwe Steinhoff John P Bourke Alan Murray

AIMS There is some dispute over the clinical significance of dispersion of ventricular repolarization measurements from the electrocardiogram. Recent studies have indicated that multichannel magnetocardiograms (MCGs), which non-invasively measure cardiac magnetic field strength from many sites above the body surface, may provide independent information from ECGs about ventricular repolarization...

2016
Vincenzo Russo Andrea Antonio Papa Anna Rago Paola D'Ambrosio Giovanni Cimmino Alberto Palladino Luisa Politano Gerardo Nigro

Sudden cardiac death in myotonic dystrophy type I (DM1) patients can be attributed to atrioventricular blocks as far as to the development of life-threatening arrhythmias which occur even in hearts with normal left ventricular systolic and diastolic function. Heterogeneity of ventricular repolarization is considered to provide an electrophysiological substrate for malignant arrhythmias. QTc dis...

Journal: :Circulation research 1975
M S Spach R C Barr

Ventricular intramural and epicardial potential distributions were measured during normal excitation and repolarization in intact dogs. Potential distributions were chosen because they can be unambiguously measured, are useful in understanding the shapes of wave forms at many specific sites, and provide a direct measure of repolarization. Unipolar wave forms were recorded from intramural and ep...

Journal: :Physiological research 2009
S N KHARIN D N SHMAKOV N A ANTONOVA

Effects of ectopic pacing on left ventricular repolarization were studied in six anesthetized open-chest chickens. In each animal, unipolar electrograms were acquired from as many as 98 sites with 14 plunge needles (seven transmural locations between epicardium and endocardium in each needle). Activation-recovery intervals (ARIs), corrected to the cycle length, were used for estimating repolari...

Journal: :Journal of pharmacological sciences 2014
Katsuyuki Kazusa Yuji Nakamura Yudai Watanabe Kentaro Ando Atsushi Sugiyama

Since information regarding the effects of pH on the extent of nifekalant-induced repolarization delay and torsades de pointes remains limited, we assessed it with a Langendorff heart model of guinea pigs. First, we investigated the effects of pH change from 7.4 to 6.4 on the bipolar electrogram simulating surface lead II ECG, monophasic action potential (MAP), effective refractory period (ERP)...

Journal: :Circulation 1998
K R Laurita S D Girouard F G Akar D S Rosenbaum

BACKGROUND Previously, we have shown that a premature stimulus can significantly modulate spatial gradients of ventricular repolarization (ie, modulated dispersion), which result from heterogeneous electrophysiological properties between cells. The role modulated dispersion may play in determining electrical instability in the heart is unknown. METHODS AND RESULTS To determine if premature st...

Journal: :The Journal of neuroscience : the official journal of the Society for Neuroscience 2014
Kevin J Ford Graeme W Davis

The strength and dynamics of synaptic transmission are determined, in part, by the presynaptic action potential (AP) waveform at the nerve terminal. The ion channels that shape the synaptic AP waveform remain essentially unknown for all but a few large synapses amenable to electrophysiological interrogation. The Drosophila neuromuscular junction (NMJ) is a powerful system for studying synaptic ...

2015
Alain J. Labro Michael F. Priest Jérôme J. Lacroix Dirk J. Snyders Francisco Bezanilla

High-frequency action potential (AP) transmission is essential for rapid information processing in the central nervous system. Voltage-dependent Kv3 channels play an important role in this process thanks to their high activation threshold and fast closure kinetics, which reduce the neuron's refractory period. However, premature Kv3 channel closure leads to incomplete membrane repolarization, pr...

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