A minimally invasive technique for the evaluation of the regulatory steps of the two major pathways of bile acid synthesis

Marina Del Puppo, Andrea Crosignani, Matteo Longo, Massimo Zuin, Mauro Podda, Giovanni Galli, Emma De Fabiani, Pierangela Ciuffreda, Enzo Santaniello, Norman B. Javitt, Marzia Galli Kienle

Research output: Contribution to journalArticle

Abstract

Background: Bile acid synthesis accounts for more than 95% of total cholesterol catabolism per day. We have developed a minimally invasive technique in humans that quantifies the rates of plasma appearance of 7α- and 27-hydroxycholesterol, representing the first steps of the "classical" and "alternative" pathways of bile acid synthesis, respectively. Methods: For this purpose, during the intravenous infusion of synthetic deuterated isotopomers of 7α-hydroxycholesterol and 27-hydroxycholesterol plasma samples are collected and analysed by a GC-MS based method that allows to quantify the exogenous/natural isotopomer ratio of the two sterols. From this data, the rates of plasma appearance of 7α- and 27-hydroxycholesterol are calculated. Results: In a group of healthy individuals steady state kinetics are obtained during a 2 h period yielding mean values of 2.0±0.8 and 3.7±0.6 mg/h for 7α- and 27-hydroxycholesterol, respectively. The data are consistent with findings using older techniques that require studies over several days. Conclusion: Considering that at steady state of the exogenous/natural isotopomer ratio the plasma appearance of the two regulatory hydroxysterols are related to the rate of bile acid synthesis via the "classical" and the "alternative" pathways, respectively, the proposed method could be used to evaluate the immediate effects of different diets and drugs and other determinants on cholesterol catabolism.

Original languageEnglish
Pages (from-to)23-31
Number of pages9
JournalClinica Chimica Acta
Volume355
Issue number1-2
DOIs
Publication statusPublished - May 2005

Keywords

  • 27-Hydroxycholesterol
  • 7α-Hydroxycholesterol
  • Bile acid synthesis
  • Mass spectrometry
  • Stable isotopes

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry

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