| Cardioinhibitory actions of clonidine assessed by cardiac vagal motoneuron recordings. | |
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MedLine Citation:
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PMID: 18475155 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Cardiac vagal activity is now considered as an important therapeutic target. However, there is a lack of direct data on how cardiac vagal motoneurons respond to parasympathomimetic agents. METHODS: Rats were anesthetized with urethane and mechanically ventilated. Single-unit activity was recorded in the nucleus ambiguus from cardiac vagal motoneurons, identified by antidromic activation from the cardiac vagal branch and their barosensitivity. RESULTS: Nitroprusside lowered systolic blood pressure, increased heart rate and inhibited cardiac vagal motoneuron activity (n = 5 cells in five rats). Clonidine 1-100 microg kg(-1) intravenously, however, lowered systolic blood pressure, but it increased cardiac vagal motoneuron activity (n = 8 cells in eight rats). It also enhanced their barosensitivity. An unsuspected further finding was that clonidine significantly increased the occurrence of cardiac vagal motoneuron firing spikes separated by short (< 30 ms) interspike intervals ('doublet'). CONCLUSION: Such grouped patterns are known to enhance neurotransmitter release. Therefore, these data provide a new mechanism by which clonidine can further potentiate parasympathetic actions on the heart. |
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Authors:
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Emil Toader; Andrei Cividjian; Nicolas Rentero; Robin M McAllen; Luc Quintin |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of hypertension Volume: 26 ISSN: 0263-6352 ISO Abbreviation: J. Hypertens. Publication Date: 2008 Jun |
Date Detail:
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Created Date: 2008-05-13 Completed Date: 2008-07-29 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8306882 Medline TA: J Hypertens Country: England |
Other Details:
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Languages: eng Pagination: 1169-80 Citation Subset: IM |
Affiliation:
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Department of Physiology, CNRS UMR5123-University of Lyon, Lyon, France. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adrenergic alpha-Agonists
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pharmacology* Animals Clonidine / pharmacology* Electrophysiology Heart / drug effects, innervation* Male Motor Neurons / drug effects* Nitroprusside / pharmacology Rats Rats, Sprague-Dawley Vagus Nerve / drug effects* Vasodilator Agents / pharmacology |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic alpha-Agonists; 0/Vasodilator Agents; 15078-28-1/Nitroprusside; 4205-90-7/Clonidine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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