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NEUROHUMORAL CONTROL OF CARDIOVASCULAR FUNCTION
1Centre de Recherche, Hôpital du Sacré-C
ur de Montréal and Faculté de Médecine, Université de Montréal, Montréal, Canada; 2Department of Pharmacology, East Tennessee State University, Johnson City, Tennessee; and 3Department of Physiology, School of Medicine, University of Oklahoma, Oklahoma City, Oklahoma
Submitted 20 January 2006 ; accepted in final form 6 June 2006
Spinal cord stimulation (SCS) applied to the dorsal aspect of the cranial thoracic cord imparts cardioprotection under conditions of neuronally dependent cardiac stress. This study investigated whether neuronally induced atrial arrhythmias can be modulated by SCS. In 16 anesthetized dogs with intact stellate ganglia and in five with bilateral stellectomy, trains of five electrical stimuli were delivered during the atrial refractory period to right- or left-sided mediastinal nerves for up to 20 s before and after SCS (20 min). Recordings were obtained from 191 biatrial epicardial sites. Before SCS (11 animals), mediastinal nerve stimulation initiated bradycardia alone (12 nerve sites), bradycardia followed by tachyarrhythmia/fibrillation (50 sites), as well as tachyarrhythmia/fibrillation without a preceding bradycardia (21 sites). After SCS, the number of responsive sites inducing bradycardia was reduced by 25% (62 to 47 sites), and the cycle length prolongation in residual bradycardias was reduced. The number of responsive sites inducing tachyarrhythmia was reduced by 60% (71 to 29 sites). Once elicited, residual tachyarrhythmias arose from similar epicardial foci, displaying similar dynamics (cycle length) as in control states. In the absence of SCS, bradycardias and tachyarrhythmias induced by repeat nerve stimulation were reproducible (five additional animals). After bilateral stellectomy, SCS no longer influenced neuronal induction of bradycardia and atrial tachyarrhythmias. These data indicate that SCS obtunds the induction of atrial arrhythmias resulting from excessive activation of intrinsic cardiac neurons and that such protective effects depend on the integrity of nerves coursing via the subclavian ansae and stellate ganglia.
intrinsic cardiac nervous system
ur de Montréal, 5400 Gouin Blvd. West, Montréal, Québec, Canada H4J 1C5, (E-mail: rene.cardinal{at}umontreal.ca)This article has been cited by other articles:
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