Mechanisms of quinidine-induced depression of maximum upstroke velocity in ovine cardiac Purkinje fibers.
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منابع مشابه
Mechanisms of quinidine-induced depression of maximum upstroke velocity in ovine cardiac Purkinje fibers.
A major advance in understanding how quinidine depresses maximum upstroke velocity (Vmax) is the Hondeghem-Katzung mathematical model which incorporates voltage-independent rate constants for binding to and unbinding from resting, open, and inactive Na channels, and a voltage shift of -40 mV for the Hodgkin-Huxley h-kinetics of quinidine-associated Na channels. Using a double microelectrode vol...
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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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We studied the local anesthetic effects of the quaternary lidocaine analogues QX-314, QX-572, and QX-222, the tertiary amine lidocaine, its analogues tocainide, 6603, 6211, and the neutral local anesthetic benzocaine to determine if molecular charge of antiarrhythmic agents influences their local anesthetic effects on heart fibers. We used standard microelectrode techniques and canine cardiac P...
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We compared the maximal upstroke velocity of action potentials in short rabbit Purkinje fibers with sodium currents measured with a two-microelectrode voltage clamp. The number of sodium channels available to open during a sudden depolarization was varied either by blockade with tetrodotoxin or by inactivation with steady depolarizations. In both cases, the maximal upstroke velocity was found t...
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We studied the role of the anticholinergic properties of disopyramide and quinidine in mediating the electrophysiological effects of these agents on isolated cardiac tissue. In right atria, disopyramide, quinidine, and procainamide administered alone elicited negative chronotropic responses. However, after cholinergic stimulation with physostigmine (1 X 10" M), disopyramide and quinidine produc...
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ژورنال
عنوان ژورنال: Circulation Research
سال: 1982
ISSN: 0009-7330,1524-4571
DOI: 10.1161/01.res.50.3.369