Type B atrial receptor discharge increases on opening a nonhypotensive arteriovenous shunt in the dog.
A vagovagal cardioacceleratory reflex is activated when an arteriovenous (a-v) shunt is opened in the dog. However, the receptors which initiate this reflex have not been localized. Type B atrial receptor excitation was considered to be a major component of this reflex. The effect of opening a femoral nonhypotensive a-v shunt (i.e., shunt open plus infusion of blood to compensate for the resultant fall in mean arterial and pulse pressure) on type B atrial receptor discharge and heart rate was therefore studied in seven anesthetized, artifically ventilated dogs with beta-adrenergic blockade. Right atrial and aortic blood pressures, heart rate, and type B atrial receptor discharge was studied before and after opening a femoral a-v shunt. On opening the a-v shunt there was a significant increase (44%) in the average activity of type B atrial receptors and a small, but significant (6.8%) increase in heart rate. A significant linear positive correlation was observed between the change in activity of type B atrial receptors and the shunt flow. The results suggest that type B atrial receptors may be one of the receptor groups that initiate this vagovagal reflex.
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001163:Arteriovenous Anastomosis / Q000502:physiology*; D001794:Blood Pressure; D004285:Dogs; D004594:Electrophysiology; D005260:Female; D006325:Heart Atria / Q000294:innervation; D006339:Heart Rate; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D012018:Reflex / Q000502:physiology