INTESTINAL ABSORPTION OF CYTIDINE DIPHOSPHATE CHOLINE AND ITS CHANGES IN THE DIGESTIVE TRACT

Abstract

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 C₅of 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 relative amount of radioactivity in individual broken-down products in the intestinal lumen and mucosa.