Cardiovascular Reflexes from Stretch of Pulmonary Vein-Atrial Junctions in the Dog

¹ Mayo Graduate School of Medicine, University of Minnesota Rochester, Minnesota; Mayo Clinic and Mayo Foundation, Department of Physiology and Biophysics

The reflex cardiovascular response to stretch of left pulmonary vein-atrial junctions was studied in anesthetized dogs in which both aortic nerves were cut and the carotid sinuses were isolated vascularly. After thoracotomy, the root of the left lung was tied and a small Silastic balloon (1.5-cm long), attached to a nylon catheter, was inserted into each of the three left pulmonary veins and tied so that its tip lay at the junction of the vein with the left atrium. In six dogs, heart rate response to balloon distension of 2.0 ml was studied over a range of initial heart rates (75 to 240 beats/min) achieved by varying the carotid sinus pressure. On distension of the balloons, slowing occurred if the initial heart rate was > 140 to 150 beats/min and acceleration if it were less. In eight dogs, aortic blood pressure and cardiac output measured before, during, and after balloon distension (0.25 to 2.0 ml) demonstrated a hyperbolic relationship between balloon volume and decrease in calculated systemic vascular resistance. All responses were abolished by vagotomy. The reflex vasodilatation was sustained and caused by decreased adrenergic activity; the reflex bradycardia or tachycardia was due to interplay of vagal and sympathetic cardiac efferents.

Submitted on September 18, 1970
Accepted on October 19, 1970

This article has been cited by other articles:

				R. Mukkamala, J.-K. Kim, Y. Li, J. Sala-Mercado, R. L. Hammond, T. J. Scislo, and D. S. O'Leary Estimation of arterial and cardiopulmonary total peripheral resistance baroreflex gain values: validation by chronic arterial baroreceptor denervation Am J Physiol Heart Circ Physiol, May 1, 2006; 290(5): H1830 - H1836. [Abstract] [Full Text] [PDF]