Gradation of the reflex response from atrial receptors

1. In anaesthetized dogs, distension of balloons so as to stimulate atrial receptors resulted in a reflex increase in heart rate. 2. Successive distensions of one, two and three balloons positioned in the left upper and middle pulmonary vein-atrial junctions and in the left atrial appendage resulted in a progressive increase in the magnitude of this response. 3. It is concluded that the magnitude of the increase in heart rate is related to the extent of receptor area stimulated.