Biphasic Effect of Cardiac Glycosides on Action Potential Duration in Isolated Purkinje Fibers
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چکیده
منابع مشابه
Depolarization and action potential duration in cardiac Purkinje fibers.
The effect of depolarization on the duration of the action potential was studied in short cardiac Purkinje fibers. Membrane potential was altered by overdriving pacemaker fibers showing spontaneous diastolic depolarization (dog), by injecting constantcurrent pulses through an intracellular microelectrode (sheep), or by voltage clamping (dog). Test action potentials were elicited at the end of 5...
متن کاملDepolarization and Action Potential Duration in Cardiac Purkinje Fibers
The effect of depolarization on the duration of the action potential was studied in short cardiac Purkinje fibers. Membrane potential was altered by overdriving pacemaker fibers showing spontaneous diastolic depolarization (dog), by injecting constantcurrent pulses through an intracellular microelectrode (sheep), or by voltage clamping (dog). Test action potentials were elicited at the end of 5...
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The effects of lidocaine and quinidine on rabbit cardiac Purkinje fibers were compared at 37 °C, using action potential and voltage clamp measurements. At therapeutic concentrations (5 /ig/ml), lidocaine shortened the duration of the action potential while quinidine lengthened it. When membrane potential was held constant between —40 and —50 mV by the application of the two-microelectrode volta...
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It is well known that cardiac action potentials are shortened by increasing the external calcium concentration (Cao). The shortening is puzzling since Ca ions are thought to carry inward current during the plateau. We therefore studied the effects of Cao on action potentials and membrane currents in short Purkinje fiber preparations. Two factors favor the earlier repolarization. First, calcium-...
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INTRODUCTION: 4-Aminopyridine (fampridine), a potassium channel blocker, has demonstrated efficacy in improving lower extremity strength and walking speed in patients with multiple sclerosis. Since in vitro electrophysiologic studies are recommended for evaluating a drug's potential to prolong the QT interval and induce such cardiac arrhythmias as Torsades de Pointes, we examined the electrophy...
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ژورنال
عنوان ژورنال: Pharmacology & Toxicology
سال: 2008
ISSN: 0901-9928
DOI: 10.1111/j.1600-0773.2001.890306.x