The nature of the atrial receptors responsible for a reflex decrease in activity in renal nerves in the dog

Abstract

In dogs anaesthetized with chloralose, distension of small balloons in the pulmonary vein-atrial junctions and left atrial appendage, to stimulate left atrial receptors, caused a reduction in activity in efferent renal nerves. This response was maintained during distension of the balloons for 30 min periods. In a 2nd group of dogs, cooling the cervical vagi in steps reduced the magnitude of the response in renal nerves. In 7 dogs, the response in 14 preparations of renal nerves was slightly reduced with the vagi at 18.degree. C and markedly reduced or abolished at 12.degree. C. The effect of cooling the vagi was the same as the effect of cooling on the increase in activity in myelinated afferent vagal fibers during similar stimulation of atrial receptors. In a 3rd group of dogs, the cervical vagi were cooled 9.degree. C. In 6 dogs, 54 preparations of renal nerves showed no significant response to distension of the balloons. In a 4th group of dogs, both vagi were sectioned in the neck. In 3 dogs, 24 preparations of renal nerves showed no response to distension of the balloons. The reduction in activity in efferent renal nerves during distension of small balloons in the pulmonary vein-atrial junctions and left atrial appendage apparently involves only atrial receptors discharging into myelinated vagal fibers.