| Alpha-adrenoceptor blockade modifies neurally induced atrial arrhythmias. | |
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MedLine Citation:
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PMID: 18716036 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Our objective was to determine whether neuronally induced atrial arrhythmias can be modified by alpha-adrenergic receptor blockade. In 30 anesthetized dogs, trains of five electrical stimuli (1 mA; 1 ms) were delivered immediately after the P wave of the ECG to mediastinal nerves associated with the superior vena cava. Regional atrial electrical events were monitored with 191 atrial unipolar electrodes. Mediastinal nerve sites were identified that reproducibly initiated atrial arrhythmias. These sites were then restimulated following 1 h (time control, n = 6), or the intravenous administration of naftopidil (alpha(1)-adrenergic blocker: 0.2 mg/kg, n = 6), yohimbine (alpha(2)-adrenergic blocker: 1 mg/kg, n = 6) or both (n = 8). A ganglionic blocker (hexamethonium: 1 mg/kg) was tested in four dogs. Stimulation of mediastinal nerves sites consistently elicited atrial tachyarrhythmias. Repeat stimulation after 1 h in the time-control group exerted a 19% decrease of the sites still able to induce atrial tachyarrhythmias. Hexamethonium inactivated 78% of the previously active sites. Combined alpha-adrenoceptor blockade inactivated 72% of the previously active sites. Bradycardia responses induced by mediastinal nerve stimulation were blunted by hexamethonium, but not by alpha(1,2)-adrenergic blockade. Naftopidil or yohimbine alone eliminated atrial arrhythmia induction from 31% and 34% of the sites (similar to time control). We conclude that heterogeneous activation of the intrinsic cardiac nervous system results in atrial arrhythmias that involve intrinsic cardiac neuronal alpha-adrenoceptors. In contrast to the global suppression exerted by hexamethonium, we conclude that alpha-adrenoceptor blockade targets intrinsic cardiac local circuit neurons involved in arrhythmia formation and not the flow-through efferent projections of the cardiac nervous system. |
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Authors:
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Louis-Philippe Richer; Alain Vinet; Teresa Kus; René Cardinal; Jeffrey L Ardell; John Andrew Armour |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't Date: 2008-08-20 |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: 295 ISSN: 0363-6119 ISO Abbreviation: Am. J. Physiol. Regul. Integr. Comp. Physiol. Publication Date: 2008 Oct |
Date Detail:
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Created Date: 2008-10-03 Completed Date: 2008-12-04 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: United States |
Other Details:
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Languages: eng Pagination: R1175-80 Citation Subset: IM |
Affiliation:
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Centre de Recherche, Hôpital du Sacré-Coeur de Montréal, Montréal, Canada. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adrenergic alpha-Antagonists
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pharmacology* Animals Arrhythmia, Sinus / physiopathology Arrhythmias, Cardiac / physiopathology* Atrial Appendage / physiopathology Atrial Fibrillation / physiopathology Atrial Flutter / physiopathology Bradycardia / physiopathology Dogs Electric Stimulation Electrocardiography Female Heart / drug effects*, innervation, physiopathology Heart Atria / drug effects, innervation, physiopathology Hexamethonium / pharmacology Male Naphthalenes / pharmacology Piperazines / pharmacology Receptors, Adrenergic, alpha / physiology* Receptors, Adrenergic, alpha-1 / antagonists & inhibitors, physiology Receptors, Adrenergic, alpha-2 / antagonists & inhibitors Tachycardia / physiopathology Tachycardia, Sinus / physiopathology Vena Cava, Superior / physiology Yohimbine / pharmacology |
| Grant Support | |
ID/Acronym/Agency:
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HL71380/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic alpha-Antagonists; 0/Naphthalenes; 0/Piperazines; 0/Receptors, Adrenergic, alpha; 0/Receptors, Adrenergic, alpha-1; 0/Receptors, Adrenergic, alpha-2; 146-48-5/Yohimbine; 57149-07-2/naftopidil; 60-26-4/Hexamethonium |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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