Evidence for prejunctional and postjunctional antagonism of the sympathetic neuroeffector junction by acetylcholine in canine cardiac Purkinje fibers
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چکیده
منابع مشابه
Prejunctional and postjunctional actions of endogenous norepinephrine at the sympathetic neuroeffector junction in canine coronary arteries.
The effects of endogenous and of exogenous norepinephrine were studied in isolated rings of canine left circumflex coronary artery and its first ventricular branch. Norepinephrine was released from adrenergic nerve endings by transmural electrical stimulation and by tyramine. In rings contracted with prostaglandin F2 alpha, transmural electrical stimulation resulted in frequency-dependent relax...
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The purpose of these experiments was to determine whether or not acetylcholine modulated the electrophysiological effects of isoproterenol on canine cardiac Purkinje fibers. Conventional microelectrode techniques were used. Predictably, isoproterenol produced shortening of action potential duration; acetylcholine significantly blunted this effect of isoproterenol. Isoproterenol restored excitab...
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The effects of acetylcholine on the electrical activity of canine cardiac Purkinje fibers.
We studied the effects of acetylcholine (ACh) on small bundles of canine cardiac Purkinje fibers exposed to normal, or low-chloride (isethionate) Tyrode's solution in a rapid superfusion system. In superfusate containing 4 mM K+, the resting potential of Purkinje fibers may be either "low," near -40 mV, or "high," near -90 mV. ACh, at 10(-6) to 10 (-5) M, increased the membrane potential from b...
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The effect of acetylcholine on automaticity of Purkinje fibers was studied in isolated canine false tendon preparations with conventional microelectrode techniques. Of 15 preparations with the control spontaneous rate of 12-60 beats/min, acetylcholine in a concentration of 0.5 mug/ml decreased the spontaneous rate by 20-87% in 13 preparations. This decrease in automaticity was due to a decrease...
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ژورنال
عنوان ژورنال: Journal of the American College of Cardiology
سال: 1984
ISSN: 0735-1097
DOI: 10.1016/s0735-1097(84)80252-1