Characterization and quantification of rat bile phosphatidylcholine by electrospray-tandem mass spectrometry.
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.
Lehmann
W D
WD
Central Spectroscopy, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, Heidelberg, 69120, Germany. wolf.lehmann@dkfz-heidelberg.de
Koester
M
M
Erben
G
G
Keppler
D
D
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*
D010713:Phosphatidylcholines; D016572:Cyclosporine