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Interactions between organic anions, micelles and vesicles in model bile systems
H J Verkade1, M A de Bruijn, M A Brink
1Groningen Institute for Drug Studies, Department of Pediatrics, University Hospital Groningen, The Netherlands.
The Biochemical Journal
|December 15, 1996
Summary
Hydrophilic organic anions inhibit biliary lipid secretion, but not by affecting micellization. In vitro studies show these compounds interact with mixed micelles but do not inhibit their formation, suggesting alternative in vivo mechanisms.
Area of Science:
- Hepatology
- Biliary Physiology
- Lipid Metabolism
Background:
- Biliary lipid secretion involves micellization and vesiculization of membrane lipids.
- Hydrophilic organic anions inhibit biliary lipid secretion in vivo without affecting bile salt secretion.
Purpose of the Study:
- To investigate if organic-anion-induced inhibition of biliary lipid secretion is due to impaired micellization.
- To evaluate the effects of organic anions on in vitro micellization models.
Main Methods:
- Utilized in vitro models using small unilamellar vesicles (SUV) of cholesterol/egg phosphatidylcholine.
- Assessed bile salt-induced fluorescence release from SUV as a measure of micellization.
- Employed ultracentrifugation and dynamic light scattering to study interactions with mixed micelles.
Main Results:
- Certain organic anions affected bile salt-induced fluorescence release from SUV, indicating interference with micellization.
- However, in vitro effects of organic anions did not correlate with their in vivo impact on biliary lipid secretion.
- Ultracentrifugation and light scattering showed organic anions interact with, but do not inhibit, mixed micelle formation.
Conclusions:
- The in vivo inhibition of biliary lipid secretion by organic anions is not mediated by the inhibition of micellization.
- The precise in vivo mechanism requires further investigation beyond micellar processes.