Concentration changes of bile acids in sequential segments of pigeon intestine and their relation to bile acid absorption.

Changes in the concentration of bile acids in sequential segments of pigeon intestine were measured. It was found that the jejunum has the highest concentration of bile acids. When the ratio of bile acids to beta-sitosterol (a non-absorbable dietary marker) was examined in contents of various segments, it was found that the ratio showed a marked decrease (86.6%) from the upper to lower jejunum while the subsequent changes in other segments were not as striking. This indicates that the jejunum is the major site of bile acid absorption in the pigeon, unlike in mammals, where the ileum has been shown to be the major site of bile acid absorption. This notion was confirmed by studies of the effect of ileal bypass in these pigeons. This surgical procedure did not significantly change the fecal excretion of bile acids or neutral sterols indicating that the jejunum is capable of maintaining a normal enterohepatic circulation of bile acids in the absence of the ileum in the pigeons.