Determination of free choline and phosphorylcholine in rat liver

A simple procedure for determination of levels of free choline and phosphorylcholine in hepatic tissue is outlined. The method makes use of the enzyme acid phosphatase to liberate choline from phosphorylcholine and incorporates the ability of choline to react with potassium triiodide to yield choline periodide for the measurement of choline and phosphorylcholine in liver. The method is accurate for both entities (recovery of 97-100% for choline and 92-98% for phosphorylcholine). For phosphorylcholine, the method is markedly simpler than other methods previously described and the results for normally fed rats are of the same order of magnitude. The applicability of the method was shown when it was demonstrated that diets containing different amounts of choline influenced the level of choline and phosphorylcholine in liver.