[Absorption of double labeled (glycerol 3H-linoleic acid 14C) native bile by phosphatidylcholines].

Double-labeled bile ([U. 3H glycerol] [1. 14C linoleic acid])--in which about 70% of labeling 14C and 80% of labeling 3H of total lipids were borne by phosphatidylcholines (PC), (isotopic ratio of these PC was equal to 1)--was introduced into the duodenum of test Rats, some of them with a bile fistula. As low amounts of the hydrolysis products of biliary PC were found in the intestinal lumen, a higher hydrolysis must occur further (brush border, enterocyte ?) because, in the mucosa, the highest labeling 14C was present as triglycerides and PC have an isotopic ratio 3H/14C higher than 1. As in the lumen the isotopic ratio 3H/14C of PC was higher than 1 and increased with the time elapsed, this finding suggests that mucosal PC were added to biliary PC (secretion or desquamation ?) unless these modifications were due to luminal micro-organisms. As test Rat bile was poorly labeled a very weak enterohepatic circulation of biliary diunsaturated PC may exist.