Document Detail


Differential chronotropic and dromotropic responses to focal stimulation of cardiac vagal ganglia in the rat.
MedLine Citation:
PMID:  12719756     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Vagal cardioinhibition is exerted through a reduction not only in the heart rate but also in the rate of propagation of the cardiac action potential and in myocardial contractility. In several species, such effects can be produced independently by selective activation of ganglia in identified 'fat pads'. In this study we investigate differential control of heart rate and atrioventricular conduction by two ganglionic clusters in the rat, a species increasingly important in studies of cardiovascular control. Epicardial sites producing low-threshold changes in P-P and P-R interval of the ECG in an arterially perfused preparation were explored with concentric bipolar stimulating electrodes. Stimulation sites centred on two principal ganglia, the sinoatrial (SA) ganglion at the junction of the right superior vena cava and right atrium, and the atrioventricular (AV) ganglion at the junction of the inferior pulmonary veins and left atrium. Stimulation of the SA ganglion decreased heart rate in all preparations, with little or no effect on AV conduction in one-third. Stimulation of the AV ganglion consistently slowed conduction without eliciting a comparable bradycardia. Responses survived blockade of ganglionic transmission by trimetaphan, with an enhanced chronotropic selectivity to SA ganglion stimulation, suggesting that co-excitation of preganglionic elements en passant may have contributed to the earlier mixed responses. Effective stimulation sites were precisely circumscribed and corresponded to principal ganglionic clusters confirmed histologically. We conclude that cardiac vagal ganglia in the rat show a topographical functional organisation and are amenable to investigation using the arterially perfused preparation.
Authors:
Karla N Sampaio; Hélder Mauad; K Michael Spyer; Timothy W Ford
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Experimental physiology     Volume:  88     ISSN:  0958-0670     ISO Abbreviation:  Exp. Physiol.     Publication Date:  2003 May 
Date Detail:
Created Date:  2003-04-29     Completed Date:  2004-01-07     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9002940     Medline TA:  Exp Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  315-27     Citation Subset:  IM    
Affiliation:
Autonomic Neuroscience Institute, Department of Physiology, Royal Free and University College Medical School, London, UK.
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MeSH Terms
Descriptor/Qualifier:
Animals
Arrhythmia, Sinus / physiopathology
Atrioventricular Node / innervation*,  physiology*
Electric Stimulation
Ganglia, Parasympathetic / cytology,  drug effects,  physiology*
Ganglionic Blockers / pharmacology
Heart Rate / physiology
Rats
Rats, Sprague-Dawley
Sinoatrial Node / innervation*,  physiology*
Stimulation, Chemical
Sympathetic Nervous System / physiology
Trimethaphan / pharmacology
Vagus Nerve / physiology*
Chemical
Reg. No./Substance:
0/Ganglionic Blockers; 7187-66-8/Trimethaphan

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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