Inhibition of fatty acid synthesis and stimulation of glycogen breakdown by vasopressin in the perfused mouse liver.

1. Vasopressin (anti-diuretic hormone, [8-arginine]vasopressin) inhibited the synthesis de novo of fatty acids (measured with (3)H(2)O and U-(14)C-labelled lactate or U-(14)C-labelled glucose) and stimulated glycogen breakdown in the perfused liver of fed mice. 2. The concentration dependence of these effects (range 200-1000muunits/ml, i.e. 0.5-2.5ng/ml) resembled that for the action on glycogen breakdown which was previously reported for rat liver. 3. The appearance of newly synthesized fatty acids in both phospholipids and triglycerides was inhibited by vasopressin, whereas synthesis of cholesterol was less affected. 4. Inhibition of hepatic lipogenesis by vasopressin is the most potent short-term hormonal action on this process yet reported. Aspects of the effect are discussed, including the lack of a role for cyclic AMP, and a possible link with vasopressin action on glycogen metabolism.