Baroreflex modulation of heart rate and initiation of atrial activation in dogs

R. B. Schuessler, T. E. Canavan, J. P. Boineau, James Lewis Cox

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


In open-chest dogs, blood pressure was regulated by titrating doses of phenylephrine and nitroprusside to determine its effect on heart rate and pacemaker location. Changes in blood pressure correlated with changes in heart rate (r = 0.86). Activation time mapping demonstrated multicentric atrial activation, with a site of origin-rate relationship. The fastest pacemakers were located in the most cranial regions and slowest in the most caudal areas. In this chloralose-morphine anesthetized model, autonomic blockade with atropine and propranolol suggests that acute baroreflex-induced changes in heart rate were mediated exclusively by either increased sympathetic or parasympathetic tone and were not associated with inhibition of the opposite system. Division of right and left thoracic cardiac nerves indicated the left sympathetics participated in the baroreflex in 50% of the animals and the left parasympathetics in 90% of the animals. Both the right sympathetics and parasympathetics were active in the baroreflex in all animals. The data demonstrate that physiological heart rate response is regulated through an extensive system of right atrial pacemakers modulated by both left and right efferent cardiac nerves.

Original languageEnglish (US)
Pages (from-to)24/3
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number3
StatePublished - 1988

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


Dive into the research topics of 'Baroreflex modulation of heart rate and initiation of atrial activation in dogs'. Together they form a unique fingerprint.

Cite this