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Transport Inhibition of Digoxin Using Several Common P-gp Expressing Cell Lines Is Not Necessarily Reporting Only on Inhibitor Binding to P-gp
- Source :
- PLoS ONE, PLoS ONE, Vol 8, Iss 8, p e69394 (2013)
- Publication Year :
- 2013
- Publisher :
- Public Library of Science, 2013.
-
Abstract
- We have reported that the P-gp substrate digoxin required basolateral and apical uptake transport in excess of that allowed by digoxin passive permeability (as measured in the presence of GF120918) to achieve the observed efflux kinetics across MDCK-MDR1-NKI (The Netherlands Cancer Institute) confluent cell monolayers. That is, GF120918 inhibitable uptake transport was kinetically required. Therefore, IC50 measurements using digoxin as a probe substrate in this cell line could be due to inhibition of P-gp, of digoxin uptake transport, or both. This kinetic analysis is now extended to include three additional cell lines: MDCK-MDR1-NIH (National Institute of Health), Caco-2 and CPT-B2 (Caco-2 cells with BCRP knockdown). These cells similarly exhibit GF120918 inhibitable uptake transport of digoxin. We demonstrate that inhibition of digoxin transport across these cell lines by GF120918, cyclosporine, ketoconazole and verapamil is greater than can be explained by inhibition of P-gp alone. We examined three hypotheses for this non-P-gp inhibition. The inhibitors can: (1) bind to a basolateral digoxin uptake transporter, thereby inhibiting digoxin's cellular uptake; (2) partition into the basolateral membrane and directly reduce membrane permeability; (3) aggregate with digoxin in the donor chamber, thereby reducing the free concentration of digoxin, with concomitant reduction in digoxin uptake. Data and simulations show that hypothesis 1 was found to be uniformly acceptable. Hypothesis 2 was found to be uniformly unlikely. Hypothesis 3 was unlikely for GF120918 and cyclosporine, but further studies are needed to completely adjudicate whether hetero-dimerization contributes to the non-P-gp inhibition for ketoconazole and verapamil. We also find that P-gp substrates with relatively low passive permeability such as digoxin, loperamide and vinblastine kinetically require basolateral uptake transport over that allowed by +GF120918 passive permeability, while highly permeable P-gp substrates such as amprenavir, quinidine, ketoconazole and verapamil do not, regardless of whether they actually use the basolateral transporter.
- Subjects :
- Digoxin
Cell Membrane Permeability
lcsh:Medicine
Gene Expression
ATP-binding cassette transporter
Pharmacology
Biochemistry
Madin Darby Canine Kidney Cells
Tetrahydroisoquinolines
Drug Discovery
polycyclic compounds
Biochemical Simulations
Biomacromolecule-Ligand Interactions
lcsh:Science
Biochemistry Simulations
Epithelial polarity
Sulfonamides
Multidisciplinary
Chemistry
Quinidine
Enzymes
Ketoconazole
Cytochemistry
Cyclosporine
Medicine
Efflux
medicine.drug
Research Article
Protein Binding
Drugs and Devices
Membrane permeability
Vinblastine
Loperamide
Dogs
medicine
Animals
Humans
Pharmacokinetics
ATP Binding Cassette Transporter, Subfamily B, Member 1
Furans
Biology
lcsh:R
Cell Membrane
Proteins
Computational Biology
Kinetics
Caco-2
Small Molecules
Verapamil
Acridines
lcsh:Q
Carbamates
Medicinal Chemistry
Caco-2 Cells
Subjects
Details
- Language :
- English
- ISSN :
- 19326203
- Volume :
- 8
- Issue :
- 8
- Database :
- OpenAIRE
- Journal :
- PLoS ONE
- Accession number :
- edsair.doi.dedup.....ebb509eac514ceda6f3d336bef37a38e