title: Heterogeneous transport of digitalis-like compounds by P-glycoprotein in vesicular and cellular assays.
abstract: Digitalis-like compounds (DLCs), the ancient medication of heart failure and Na,K-ATPase inhibitors, are characterized by their toxicity. Drug-drug interactions (DDIs) at absorption and excretion levels play a key role in their toxicity, hence, knowledge about the transporters involved might prevent these unwanted interactions. In the present study, the transport of fourteen DLCs with human P-glycoprotein (P-gp; ABCB1) was studied using a liquid chromatography-mass spectrometry (LC-MS) quantification method. DLC transport by P-gp overexpressing Madin-Darby canine kidney (MDCK) and immortalized human renal cells (ciPTEC) was compared to vesicular DLC transport. Previously, we identified convallatoxin as a substrate using membrane vesicles overexpressing P-gp; however, we could not measure transport of other DLCs in this assay (Gozalpour et al., 2014a). Here, we showed that lipophilic digitoxin, digoxigenin, strophanthidin and proscillaridin A are P-gp substrates in cellular accumulation assays, whereas the less lipophilic convallatoxin was not. P-gp function in the cellular accumulation assays depends on the entrance of lipophilic compounds by passive diffusion, whereas the vesicular transport assay is more appropriate for hydrophilic substrates. In conclusion, we identified digitoxin, digoxigenin, strophanthidin and proscillaridin A as P-gp substrates using cellular accumulation assays and recognized lipophilicity as an important factor in selecting a suitable transport assay.
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, The Netherlands.
authors.forename: Elnaz
authors.initials: E
authors.lastname: Gozalpour
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, The Netherlands.
authors.forename: Martijn J
authors.initials: MJ
authors.lastname: Wilmer
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, The Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: Bilos
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, The Netherlands.
authors.forename: Rosalinde
authors.initials: R
authors.lastname: Masereeuw
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, The Netherlands.
authors.forename: Frans G M
authors.initials: FG
authors.lastname: Russel
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, The Netherlands. Electronic address: jan.koenderink@radboudumc.nl.
authors.forename: Jan B
authors.initials: JB
authors.lastname: Koenderink
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000378:metabolism; D000818:Animals; D001681:Biological Assay; D001692:Biological Transport; D002301:Cardiac Glycosides / Q000494:pharmacology*; D002460:Cell Line; D004285:Dogs; D006801:Humans; D061985:Madin Darby Canine Kidney Cells
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D002301:Cardiac Glycosides
keywords: Cellular assay; Digitalis-like compounds; MDCK; P-glycoprotein; Vesicular assay; ciPTEC