title: Cyclic fluctuations in fasting serum bile acid levels detected with a sensitive enzyme/bioluminescent assay.
abstract: A sensitive two-step bioluminescent assay for total serum bile acids was developed using commercially available enzymes. In the first step, the bile acids present in 10 microL of alkali-treated serum were oxidised at pH 9.5 by high purity 3 alpha-hydroxysteroid dehydrogenase to form NADH. Then, NADH was quantitated at pH 6.5 under optimal conditions for bioluminescence using FMN:NADH oxidoreductase and luciferase from Photobacterium fischeri. The enzyme/bioluminescent assay correlated well with gas-liquid chromatography and radioimmunoassay methods. Assay of fasting sera in eight healthy subjects revealed cyclic fluctuations in bile acid concentrations which were inversely related to gallbladder volume. These results provide biochemical evidence for interdigestive partial gallbladder emptying as a normal physiological process.
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000032:analysis; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific); D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001647:Bile Acids and Salts / Q000097:blood*; D002849:Chromatography, Gas; D004591:Electrophoresis, Polyacrylamide Gel; D004798:Enzymes / Q000032:analysis; D005260:Female; D005704:Gallbladder / Q000502:physiology; D006801:Humans; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D009243:NAD / Q000097:blood; D011863:Radioimmunoassay
chemical_list: D001647:Bile Acids and Salts; D004798:Enzymes; D009243:NAD; D015096:3-Hydroxysteroid Dehydrogenases; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)