Donate Help Contact The AHA Sign In Home
American Heart Association
Circulation
Search: search_blue_button Advanced Search
« Previous Article | Table of Contents
Circulation. 1983;67:1378-1387

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowRequest Permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Rozanski, G. J.
Right arrow Articles by Randall, W. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Rozanski, G. J.
Right arrow Articles by Randall, W. C.

Circulation, Vol 67, 1378-1387, Copyright © 1983 by American Heart Association

ARTICLES

Functional characteristics of sinoatrial and subsidiary pacemaker activity in the canine right atrium

GJ Rozanski, SL Lipsius and WC Randall

A canine in vitro right atrial preparation was developed to study the functional characteristics of subsidiary atrial pacemaker (SAP) activity and to compare them with those of sinoatrial node (SAN) activity. Extracellular bipolar electrodes were used to estimate the site of earliest activation and monitor spontaneous rate. Ligation of the SAN artery at the midportion of the sulcus terminalis suppressed SAN activity and usually (73.5%) elicited SAP activity in a well- defined region of the inferior atrium. SAP activity in this region required a "threshold" concentration of norepinephrine (10(-8) M) in the Tyrode's perfusate. In response to all concentrations of norepinephrine tested, SAN activity attained a greater maximum spontaneous rate than SAP activity. Cholinergic stimulation with acetylcholine or eserine elicited a greater negative chronotropic response from SAP than SAN activity. Overdrive pacing suppressed SAP activity to a significantly greater extent than SAN activity. We conclude that this in vitro preparation can be useful for studying the pharmacology and electrophysiology of subsidiary atrial pacemakers that emerge after suppression of SAN activity. In contrast to SAN activity, SAP activity requires norepinephrine and is more sensitive than SAN activity to acetylcholine and overdrive pacing. Consequently, after loss of SAN function, autonomic modulation of SAP activity may result in atrial dysrhythmias and prolonged periods of overdrive suppression.




Circulation Home | Subscriptions | Archives | Feedback | Authors | Help | AHA Journals Home | Search
Copyright © 1983 American Heart Association, Inc. All rights reserved. Unauthorized use prohibited.