Tachybradycardia in the isolated canine right atrium induced by chronic sympathetic stimulation and pacemaker current inhibition
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منابع مشابه
Tachybradycardia in the isolated canine right atrium induced by chronic sympathetic stimulation and pacemaker current inhibition.
The mechanisms of sinoatrial node (SAN) dysfunction in patients with chronically elevated sympathetic tone and reduced pacemaker current (I(f); such as heart failure) are poorly understood. We simultaneously mapped membrane potential and intracellular Ca(2+) in the Langendorff-perfused canine right atrium (RA). Blockade of either I(f) (ZD-7288) or sarcoplasmic reticulum Ca(2+) release (ryanodin...
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Cholinergic agonists and vagal stimulation potentiate the inducibility of atrial fibrillation. To describe the activation patterns and determine the mechanisms that sustain cholinergic fibrillation, tachyarrhythmias were induced with a single extrastimulus in the isolated Krebs-Henseleit-perfused canine right atrium (n = 11) at increasing concentrations of acetylcholine (from 10(-7.5) to 10(-4....
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A canine in vitro right atrial preparation was developed to study the functional characteristics of subsidiary atrial pacemaker (SAP) activity and to compare them with those of sinoatrial node (SAN) activity. Extracellular bipolar electrodes were used to estimate the site of earliest activation and monitor spontaneous rate. Ligation of the SAN artery at the midportion of the sulcus terminalis s...
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The effects of potassium chloride on inotropic and chronotropic activity were investigated in five isolated canine atrium preparations which were suspended in a bath and perfused with arterial blood from the carotid artery of the heparinized support dog. Potassium chloride administered into the cannulated sinus node artery in a dose range of 100 mug-1 mg produced a dose-related negative inotrop...
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BACKGROUND Since the atria are thin-walled structures, most studies that have examined the spread of activation in the atria have assumed that they behave electrophysiologically as a two-dimensional surface. It was the objective of this study to determine whether or not this assumption is true by simultaneously mapping the epicardial and endocardial activation sequences in the right atrium. M...
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ژورنال
عنوان ژورنال: American Journal of Physiology-Heart and Circulatory Physiology
سال: 2010
ISSN: 0363-6135,1522-1539
DOI: 10.1152/ajpheart.00347.2010