Determination of 7 alpha-hydroxy-4-cholesten-3-one level in plasma using isotope-dilution mass spectrometry and monitoring its circadian rhythm in human as an index of bile acid biosynthesis

J Chromatogr B Biomed Appl. 1994 May 13;655(2):179-87. doi: 10.1016/0378-4347(94)00107-3.

Abstract

A highly sensitive and specific method has been developed for determination of the level of 7 alpha-hydroxy-4-cholesten-3-one in plasma. This method is based on a stable isotope-dilution technique by gas chromatography-selected-ion monitoring mass spectrometry. 7 alpha-Hydroxy-4-cholesten-3-one was extracted from plasma by saltingout extraction, and then purified by serial solid-phase extractions. The extract was treated with O-methylhydroxyl-amine hydrochloride and then dimethylethylsilylated. The resulting methyloxime-dimethylethylsilyl ether derivative was quantified by gas chromatography-selected-ion monitoring mass spectrometry with a high-resolution mode. The plasma levels of 7 alpha-hydroxy-4-cholesten-3-one were correlated with the cholesterol 7 alpha-hydroxylase activity to a higher degree than those of any other form of 7 alpha-hydroxycholesterol (r = 0.84, n = 16, p < 0.0001). The present method was applied to monitor the circadian rhythm of 7 alpha-hydroxy-4-cholesten-3-one levels in human plasma. It was concluded that the plasma level of 7 alpha-hydroxy-4-cholesten-3-one is a useful index for the monitoring of bile acid biosynthesis in the human liver.

MeSH terms

  • Adult
  • Aged
  • Bile Acids and Salts / biosynthesis*
  • Cholelithiasis / blood
  • Cholestenones / blood*
  • Cholesterol / blood
  • Cholesterol 7-alpha-Hydroxylase / metabolism
  • Circadian Rhythm*
  • Gastrointestinal Neoplasms / blood
  • Humans
  • Hydroxycholesterols / blood
  • Kinetics
  • Liver / enzymology
  • Male
  • Mass Spectrometry / methods*
  • Mass Spectrometry / statistics & numerical data
  • Middle Aged
  • Reproducibility of Results

Substances

  • Bile Acids and Salts
  • Cholestenones
  • Hydroxycholesterols
  • 7 alpha-hydroxy-4-cholesten-3-one
  • cholest-5-en-3 beta,7 alpha-diol
  • Cholesterol
  • Cholesterol 7-alpha-Hydroxylase