Measurement of the Transport Activities of Bile Salt Export Pump Using LC-MS

The high performance liquid chromatography–electrospray ionization–mass spectrometry method has been applied to the measurement of bile acid transport activities in membrane vesicles obtained from a human bile salt export pump expressing Sf9 cells. The amounts of bile acids transported using the human bile salt export pump expressing Sf9 cells were determined using liquid chromatography–electrospray ionization–mass spectrometry method and the values of the kinetic parameters were determined to be comparable with those obtained using radioisotope-labeled substrates. The developed method was highly useful for the measurements of bile acid transport activities.