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The atrial receptors responsible for the decrease in plasma vasopressin caused by distension of the left atrium in
Abstract:
In dogs anaesthetized with chloralose, the effects of cooling the cervical vagi on the reflex decrease in plasma concentration of vasopressin, caused by distension of a large balloon in the lumen of the left atrium, were examined. Distension of the balloon in ten dogs with the vagi at 37 degrees C resulted in a decrease in plasma concentration of vasopressin and, as before, an increase in urine flow. The responses were not significantly affected by cooling to 16-18 degrees C but were abolished at 9 degrees C. At 16-18 degrees C the increase in activity in myelinated vagal afferent fibres is largely unchanged and at 9 degrees C is abolished (Kappagoda, Linden & Sivananthan, 1979; Sivananthan, Kappagoda & Linden, 1981). It is concluded that the decrease in plasma concentration of vasopressin during distension of the left atrium is mediated by the Paintal-type atrial receptors with myelinated vagal afferent fibres.