The metabolic fate of lysolecithin administered into the rat duodenal lumen was investigated, using lyso-(1-acyl)-lecithin labeled with (methyl-
14C)-choline or (2-
3H)-glycerol.
Lecithin was the most radioactive in phospholipids of the tissues of the intestine and liver. Lecithin was subfractionated into 4 molecular species according to the degree of unsaturation. No definite evidence was obtained for the difference in
14C- and
3H-specific activities between the subfractions of intestinal lecithin.
In liver lecithin, the
14C-specific activity was much higher in monoenoic and dienoic subfractions than in the other polyenoic ones.
Appreciable portions of
3H-activity were incorporated into intestinal neutral lipids. The activity was the highest in triglyceride and moderate in diglyceride but showed only a trace in monoglyoeride.
The
14C-activity was appreciably incorporated into the acid soluble fraction. Three radioactive compounds were detected in both tissues. In the intestine at 10 minutes' period, the activity was highest in glyceryl-phosphoryl-choline, remarkable in phosphoryl-choline and showed only a trace in free choline, but during 90 minutes' period the three compounds showed almost the same level of activity.
In the liver at 90 minutes, the radioactivity was the highest in phosphoryl-choline, moderate in oholine, but negligible in glyceryl-phosphoryl-choline.
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