HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 93/2/165    most recent expphysiol.2007.041178v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Armour, J. A. Search for Related Content PubMed PubMed Citation Articles by Armour, J. A.

¹ Centre de recherche, Hôpital du Sacré-Cœur de Montréal and Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada

Abstract

It is hypothetized that the heart possesses a nervous system intrinsic to it that represents the final relay station for the co-ordination of regional cardiac indices. This ‘little brain’ on the heart is comprised of spatially distributed sensory (afferent), interconnecting (local circuit) and motor (adrenergic and cholinergic efferent) neurones that communicate with others in intrathoracic extracardiac ganglia, all under the tonic influence of central neuronal command and circulating catecholamines. Neurones residing from the level of the heart to the insular cortex form temporally dependent reflexes that control overlapping, spatially determined cardiac indices. The emergent properties that most of its components display depend primarily on sensory transduction of the cardiovascular milieu. It is further hypothesized that the stochastic nature of such neuronal interactions represents a stabilizing feature that matches cardiac output to normal corporal blood flow demands. Thus, with regard to cardiac disease states, one must consider not only cardiac myocyte dysfunction but also the fact that components within this neuroaxis may interact abnormally to alter myocyte function. This review emphasizes the stochastic behaviour displayed by most peripheral cardiac neurones, which appears to be a consequence of their predominant cardiac chemosensory inputs, as well as their complex functional interconnectivity. Despite our limited understanding of the whole, current data indicate that the emergent properties displayed by most neurones comprising the cardiac neuroaxis will have to be taken into consideration when contemplating the targeting of its individual components if predictable, long-term therapeutic benefits are to accrue.

(Received 26 October 2007; accepted after revision 31 October 2007; first published online 2 November 2007)
Corresponding author J. A. Armour: Hôpital du Sacré-Coeur de Montréal, Research Center, 5400 Gouin Boulevard West, Montreal, QC H4J 1C5, Canada. Email: drewarmour{at}hotmail.com

This article is based on the Carl Ludwig Distinguished Lecture of the American Physiological Societies, Neural Control & Autonomic Regulation Section that was delivered at the Annual Experimental Biology Congress in Washington, DC, on 29th April 2007.