Stimulation by vasopressin of glycogen breakdown and gluconeogenesis in the perfused rat liver.

1. Vasopressin (anti-diuretic hormone, [8-arginine]vasopressin) stimulated the breakdown of glycogen in perfused livers of fed rats, at concentrations (50-600muunits/ml) that have been reported in the blood of intact rats, especially during acute haemorrhagic shock. 2. In perfused livers from starved rats, vasopressin (30-150muunits/ml) stimulated gluconeogenesis from a mixture of lactate, pyruvate and glycerol. 3. Vasopressin prevented accumulation of liver glycogen in the perfused liver of starved rats, or in starved intact rats. 4. The action of vasopressin on hepatic carbohydrate metabolism thus resembles that of glucagon; the minimum effective circulating concentrations of these hormones are of the same order (100pg/ml). 5. The stimulation of hepatic glucose output by vasopressin is discussed in connexion with the release of glucose and water from the liver.