Bile Acids in Portal Blood of Rats Fed Different Diets and Cholestyramine

Abstract

Dihydroxy and trihydroxy bile acids in the portal blood and intestinal contents of rats were analyzed by a gas chromatographic method. Cholic, hyodoxycholic, β‐muricholic, chenodeoxycholic and deoxycholic acids made up about 65, 13, 12, 5 and 5% respectively of the bile acids in portal serum. When a commercial pellet food was given about 65% of these acids were conjugated as compared with 90% when a low‐bulk semisynthetic diet was fed. The ratios between the different bile acids were similar in small intestinal contents and portal serum. The proportion of free bile acids and of hyodeoxycholic and deoxycholic acids was higher in portal blood draining the distal part of the intestine. The total bile acid concentration was about 60 μM with large variations partly due to sampling conditions. Cholestyramine, 1% in the diet, did not change the concentration or composition of the bile acids determined. The data obtained do not support the theory that the production of bile acids from cholesterol is regulated through a direct feedback inhibition by the bile acids returned to the liver via the portal blood.