Plasma vasopressin concentration in the anaesthetized dog before, during and after atrial distension

Plasma vasopressin (AVP) concentration in dogs anaesthetized with chloralose was measured by radioimmunoassay and was within the range of 2-5 pg/ml. during control periods. Distension of the left atrium led within 2 min to a fall in plasma AVP concentration which reached a steady lower value within 4 min. After cessation of atrial distension the AVP concentration returned to pre-distention values within 4 min. Cooling the cervical vagosympathetic nerves to 8-10 degrees C led to a rise in plasma AVP concentration. Atrial distension during cooling of the vagi resulted in a further increase of plasma AVP concentration.