Is there an entero-hepatic circulation of the bile phospholipids?

Bile previously labeled with tritiated oleic acid (the main radioactivity was on bile phospholipids) was mixed with pure isolated phospholipids previously labeled with¹⁴C oleic acid; this mixture was perfused during 6 or 23 hr into the duodenum of test rats bearing a bile fistula. At the time of decapitation, in the small intestine a large hydrolysis of the¹⁴C phospholipids was found. In contrast no bile phospholipid hydrolysis was observed. In the collected bile samples of the test rats, no¹⁴C could be detected (this means a very large decrease of the¹⁴C fatty acids specific activities by the body fatty acids), and the tritiated fatty acids specific activities were only 2.5–12 times lower than in the perfused bile. These results can be explained, assuming that the bile phospholipids enter in an entero-hepatic circulation and are preserved from the dilution in a large pool of lipids.