Intestinal absorption of bile acids in the pig. Role of distal bowel

The role of distal bowel in intestinal recycling of total bile acids was investigated in five healthy, conscious, normally fed pigs. Total bile acids appearing in the portal blood of fistulated animals were measured when bile irrigated the whole bowel (control period) and again when it was diverted at 1 m proximal to the ileocecal valve so that enterohepatic circulation was limited to only the last meter of ileum plus large bowel. Measurements were taken just after the bile had been diverted and then four days later when a new steady state was reached. Under steady-state conditions bile acid reabsorption rate in distal bowel was 20% of the normal rate. This result has been discussed taking into account the high but transient ability of distal bowel to spare bile acids measured in the first hours after bile diversion. The present experiment, together with some other in vivo trials on small laboratory animals, indicate that the proximal bowel may take a large part in bile acid absorption and that we need to reevaluate the notion that bile acid absorption takes place mainly in distal bowel.