title: Characterization and quantification of rat bile phosphatidylcholine by electrospray-tandem mass spectrometry.
abstract: Rat bile phosphatidylcholine was structurally characterized and quantified by electrospray mass spectrometry using a triple quadrupole instrument. All results were obtained by direct analysis of an unprocessed total lipid extract from rat bile. Structural characterization of phosphatidylcholine was achieved by collision-induced dissociation of [M + Cl]- ions observed in the negative-ion electrospray mass spectrum. Quantification of phosphatidylcholine was performed in the positive-ion mode using precursor ion scanning of m/z 184 and dimyristoyl-phosphatidylcholine as internal standard. Using this new methodology, the effect of cyclosporin A on biliary phosphatidylcholine excretion in the rat was investigated. After intravenous administration of cyclosporin A (25 mg/kg body wt) the phosphatidylcholine level in bile was reduced to about 30% of the control level. This suggests an inhibition by cyclosporin A of the translocation of phosphatidylcholine across the hepatocyte canalicular membrane which is mediated by the Mdr2 P-glycoprotein.
authors.affiliation: Central Spectroscopy, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, Heidelberg, 69120, Germany. wolf.lehmann@dkfz-heidelberg.de
authors.forename: W D
authors.initials: WD
authors.lastname: Lehmann
authors.forename: M
authors.initials: M
authors.lastname: Koester
authors.forename: G
authors.initials: G
authors.lastname: Erben
authors.forename: D
authors.initials: D
authors.lastname: Keppler
mesh_terms: D000818:Animals; D001646:Bile / Q000737:chemistry*; D016572:Cyclosporine / Q000494:pharmacology; D008297:Male; D010713:Phosphatidylcholines / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D018629:Spectrometry, Mass, Secondary Ion / Q000379:methods*
chemical_list: D010713:Phosphatidylcholines; D016572:Cyclosporine