Intestinal absorption of cytidine diphosphate choline and its changes in the digestive tract

Intestinal absorption of cytidine diphosphate choline (CDP-choline), its structural changes in the digestive tract, and hepatic uptake have been investigated in rats using 14C-labeled (14CH3 attached to N of choline) and 3H-labeled (at C5 of pyrimidine) compounds. The results indicate that: 1)CDP-choline is relatively stable in the stomach, but is quickly degraded into cytidine and choline in the intestine; 2) The hepatic uptakes of 14C and 3H reach the maximum in two to three hours after oral administration; 3) Whereas the amount of 14C remaining in the gut is inversely related to the hepatic uptake, no similar correlation is seen with 3H-labeled CDP-choline, and 4) Extrahepatic uptake of 14C and 3H is very small. The possibility of phosphorylation in the mucosa of choline and cytidine has been discussed, based on the differences in individual broken-down products in the intestinal lumen and mucosa.