Mechanism of Action of Choline

stance, it may be due to an increased synthesis, a decreased oxidation in the liver, an increased mobilization from the depots to the liver or a decreased mobilization from the liver to other tissues. Accordingly, the lipotropic action of choline could be explained by a stimulation or inhibition of any one or more of such processes. During the last twenty years a number of investigators have attempted to choose between these various interpretations by giving heavy water,’4 or, more recently, C’4-acetate46 to animals with or without a deficiency of choline, and then comparing the amounts and concentrations of the newly synthesized fatty acids in the livers and depots of these two groups of animals. The results of recent experiments carned out in our laboratory on mice fed labeled acetate6 are essentially in agreement with those previously obtained by others. In all animals the specific activities of the fatty acids were higher in the liver than in the muscle, suggesting that the labeled fatty acids which accumulate in the liver are chiefly synthesized in this tissue