Long-lasting inhibitory effects of cyclosporin A, but not tacrolimus, on OATP1B1- and OATP1B3-mediated uptake.
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Cyclosporin A (CsA) causes a number of clinically relevant drug-drug interactions (DDIs) by inhibiting OATP1B1 and OATP1B3. In the present study, long-lasting inhibitory effects of CsA on these transporters were examined in comparison to tacrolimus (TCR). OATP1B1- and OATP1B3-expressing HEK293T cells, OATP1B1-expressing MDCK II cells, and human hepatocytes were preincubated with CsA or TCR, and uptake studies were carried out in their presence or absence. Western blot or immunohistochemical studies were done in OATP1B1-expressing HEK293T cells. The pretreatment of OATP1B1- and OATP1B3-expressing cells with 0.5-10 microM CsA, but not TCR, resulted in a reduction in their activity, even after washing out CsA from the incubation media. Preincubating the cells with CsA significantly enhanced its inhibitory effects on OATP1B1 and OATP1B3 by coincubation at 0.1-1 microM. Preincubation with 1 microM CsA caused a reduction in OATP1B1 activity for at least 18 h after its removal. The expression of OATP1B1 was not affected by incubation with CsA and no obvious change in its intracellular localization was observed. The long-lasting inhibition by CsA was also observed in human hepatocytes. Thus, CsA has a long-lasting inhibitory effect on OATP1B1 and OATP1B3. It may attribute to the clinically relevant DDIs between OATP substrates and CsA. (+info)
Multiple post-translational modifications regulate E-cadherin transport during apoptosis.
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Role of P-glycoprotein in intestinal absorption of FB2, a promising Abl/Src dual tyrosine kinase inhibitor.
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FB2 is a promising Abl/Src dual tyrosine kinase inhibitor which is designed to overcome imatinib resistance. The present study aims to investigate the role of P-glycoprotein (P-gp) in intestinal absorption of FB2 with an in vitro Caco-2 and MDCK-MDR1 cell model, single-pass intestinal perfusion model and in vivo pharmacokinetics with a selective inhibitor in rats. The results from Caco-2 cells indicated that P(appB-A) of FB2 and its metabolites (FB7 and FB10) were much higher than P(appA-B), and the efflux ratio (P(appB-A)/P(appA-B)) of FB2, FB7 and FB10 were decreased with P-gp inhibitor LSN335984; FB2 was further confirmed to be the substrate of P-gp in MDCK-MDR1 cells. In addition, P(blood) of FB2 and the cumulative amount of metabolites in mesenteric blood were elevated in a concentration-dependent manner in rat intestinal perfusion, while both of them were remarkably increased when P-gp inhibitor was added. The F(oral) of FB2 was increased to 24.52% when orally coadministrated with verapamil (25 mg/kg), which was significantly higher than that (5.7%) by FB2 (18 mg/kg) alone in rats. The AUC and Cmax of FB2 metabolites (FB7 and FB10) were also increased in the presence of verapamil. In conclusion, the low bioavailability of FB2 is believed to be partially due to the P-gp mediated active efflux and first-pass metabolism in the rat intestine. (+info)
Swine influenza virus infection dynamics in two pig farms; results of a longitudinal assessment.
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Impact of P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) on the brain distribution of a novel BRAF inhibitor: vemurafenib (PLX4032).
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