The action of choline and fat on lipide phosphorylation in the liver.

Earlier studies with the aid of radioactive phosphorus as an indicator have shown that the rate of the formation of phospholipides in the liver of rats was definitely higher when the diet contained large proportions of fats (1). It seems probable that in these experiments adequate amounts of choline or choline precursors were available to the animals. On the other hand the administration of choline to rats on low protein diets markedly stimulates the turnover of liver phospholipides as measured by the introduction into their molecule of either radioactive phosphorus (24) or isotopic choline nitrogen (5). In these studies only high fat diets were employed. In the present investigation an attempt has been made to study, under strictly comparable conditions, the action of single large doses of choline or fat, or both, on the formation of phospholipides in the liver of rats previously maintained on a low fat, low protein diet. For the purpose of comparison a few experiments were made on rats maintained on an adequate stock diet. Moreover, in most of our animals, determinations were also carried out on the lipides of the small intestine. It was hoped that the results of these determinations could supply additional information on the lipide phosphorylation in the intestine after administration of choline and fat. Preliminary findings on this subject have already been described and discussed briefly (6).