Relationship between hepatic cholesterol synthesis and biliary cholesterol secretion in man: hepatic cholesterol synthesis is not a major regulator of biliary lipid secretion.
1. To examine the role of newly synthesized cholesterol as a determinant of bile lipid secretion, both hepatic cholesterol synthesis (as judged by the activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, EC 1.1.1.34; HMGCoAR) and steady state biliary cholesterol output were measured in nine patients. 2. HMGCoAR levels varied four fold (9-40 pmol min-1 mg-1) and biliary cholesterol secretion 2.5-fold (0.60-1.15 mumol h-1 kg-1) but there was no correlation between these two variables (r = 0.18; P greater than 0.05) nor between biliary bile acid output and HMGCoAR activity (r = 0.34; P greater than 0.05). 3. There was, however, a linear relationship between bile acid and phospholipid secretion (r = 0.77; P less than 0.001) and between bile acid and cholesterol secretion (r = 0.69; P less than 0.05). 4. These results suggest that HMGCoAR activity is not a major determinant of cholesterol secretion nor at these secretion rates is HMGCoAR activity related to bile acid return to the liver.
D001647:Bile Acids and Salts / Q000378:metabolism*; D002769:Cholelithiasis / Q000378:metabolism; D002784:Cholesterol / Q000032:analysis / Q000096:biosynthesis* / Q000378:metabolism; D005260:Female; D006706:Homeostasis; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D025782:Hydroxymethylglutaryl-CoA-Reductases, NADP-dependent; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male
D001647:Bile Acids and Salts; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases; D025782:Hydroxymethylglutaryl-CoA-Reductases, NADP-dependent