Changes of the pattern of biliary bile acids during isolated rat liver perfusion

In spite of the extensive use of isolated perfused liver systems for bile acid related studies, the composition of biliary bile acids during liver perfusion is not well known. Using recently developed bioluminescence assays for 3 alpha-OH-, 7 alpha-OH-, and 12 alpha-OH- bile acids we studied the hydroxylation pattern of bile acids in bile during 90 minutes perfusion of isolated rat liver without added bile acid load. At the beginning 7 alpha-hydroxylated bile acids comprised more than 50% of total bile acids from male livers and more than 90% from female livers, this percentage declined rapidly during the first 40-50 minutes of perfusion to values between 10 and 20%. 12 alpha-hydroxylated bile acids comprised between 15 and 30% of the total at beginning of the perfusion and decreased to about 10% after 40 minutes. Sex differences as well as the influence of the duration of perfusion should be considered when the isolated perfused rat liver is used for bile acid related studies.