Thermal stimulation of intra-abdominal veins in conscious rabbits.

1. Infusions of hot and cold Hartmann's solution were given into the hepatic portal vein and inferior vena cava of conscious rabbits. Similar infusions were given into an ear vein as controls. The time integral of the displacement of brain temperature was measured. 2. There was no evidence for the presence of warm sensors in the inferior vena cava, portal vein, liver or hepatic vein, and no evidence for a concentration of cold sensors in the inferior vena cava. 3. There may be cold-sensitive elements in the portal vein or the tissue perfused by blood passing through it.