specific radioactivities of choline , acetylcholine , phosphocholine , lecithin , lysolecithin , and glycerophosphorylcholine have been measured in brain , blood , liver , and muscle after the intravenous injection of three labeled precursors : choline , methyl-labeled methionine , and ethanolamine .
C0031617
lecithin
C0017889
glycerophosphorylcholine