Assessment of Bile Salt Export Pump (BSEP) Inhibition in Membrane Vesicles Using Radioactive and LC/MS-Based Detection Methods.

The bile salt export pump (BSEP, ABCB11) belongs to the ATP-binding-cassette superfamily of transporters and is predominately found in the liver. BSEP is an efflux transporter that plays a critical role in the secretion of bile salts into the bile. Inhibition of BSEP function by drugs can result in the buildup of bile salts in the liver and eventually leads to cholestasis and drug-induced liver injury (DILI). DILI is a major cause of withdrawal of drugs from the pharmaceutical market and accounts for >50% of acute liver failures. Therefore, early detection of BSEP inhibition by drugs can help to mitigate the possibility of BSEP-associated liver injury. This unit describes two assays that investigate the relationship between drug interference with BSEP function and liver injury using membrane vesicles prepared from Hi5 insect cells transfected with human BSEP. Comprehensive protocols for assessing BSEP inhibition in a 384-well format using radiolabeled and liquid chromatography/mass spectrometry (LC/MS)-based detection methods are described. © 2017 by John Wiley & Sons, Inc.