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The plasma level of 7α‐hydroxy‐4‐cholesten‐3‐one reflects the activity of hepatic cholesterol 7α‐hydroxylase in man
Author(s) -
Axelson Magnus,
Björkhem Ingemar,
Reihnér Eva,
Einarsson Kurt
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80688-y
Subject(s) - cholestyramine , medicine , ursodeoxycholic acid , endocrinology , chenodeoxycholic acid , enzyme , bile acid , cholesterol , chemistry , sterol , microsome , enzyme assay , biology , biochemistry
Circulating levels of 7α‐hydroxy‐4‐cholesten‐3‐one have been compared with activities of the rate‐limiting enzyme in bile acid synthesis, microsomal cholesterol 7α‐hydroxylase, measured in liver biopsies obtained from patients undergoing surgery for gallstone disease. Some patients were treated with cholestyramine or bile acids prior to operation in order to alter the feed‐back inhibition of the enzyme. The levels of the sterol were similar in untreated patients and in patients treated with ursodeoxycholic acid (median concentration 17 and 13 ng/ml, respectively), and so were the activities of the enzyme (median activity 7.0 and 5.5 pmol/min/mg protein, respectively). The sterol levels and enzyme activities were significantly increased in patients treated with cholestyramine (91 ng/ml and 45 pmol/min/mg protein) and decreased in patients treated with chenodeoxycholic acid (<2.0 ng/ml and 0.7 pmol/min/mg protein). There was a strong positive correlation ( r =0.90, P <0.00001) between levels of 7α‐hydroxy‐4‐cholesten‐3‐one in plasma and the activities of cholesterol 7α‐hydroxylase in the whole patient group. The results show that analysis of 7α‐hydroxy‐4‐cholesten‐3‐one in plasma is a sensitive and convenient method to determine relative rates of bile acid production in man.