Cellular Accumulation of Cholyl-Glycylamido-Fluorescein in Sandwich-Cultured Rat Hepatocytes: Kinetic Characterization, Transport Mechanisms, and Effect of Human Immunodeficiency Virus Protease Inhibitors
- 1 July 2008
- journal article
- Published by Elsevier in Drug Metabolism and Disposition
- Vol. 36 (7) , 1315-1321
- https://doi.org/10.1124/dmd.107.019398
Abstract
The present study was aimed at characterizing the in vitro cellular uptake mechanism and kinetics of the bile salt analog cholylglycylamido-fluorescein (CGamF) in sandwich-cultured rat hepatocytes (SCRHs). Concentration-dependent inhibition of active CGamF accumulation by seven human immunodeficiency virus (HIV) protease inhibitors (PIs) was also determined and compared with inhibition data obtained with taurocholate (TC) as a substrate. A Km value of 9.3 ± 2.6 μM was obtained for saturable CGamF accumulation in SCRHs. The organic anion-transporting polypeptide (Oatp) inhibitor rifampicin (100 μM) inhibited CGamF (1 μM) accumulation in SCRHs by 72%; sodium depletion did not further reduce CGamF accumulation. In contrast, TC accumulation was reduced by only 25% in the presence of rifampicin, whereas additional sodium depletion resulted in a complete loss of TC accumulation. These data imply that Oatp(s) and sodium taurocholate-cotransporting polypeptide preferentially mediate hepatic uptake of CGamF and TC, respectively. Coincubation of CGamF with HIV PIs (amprenavir, atazanavir, darunavir, indinavir, nelfinavir, ritonavir, saquinavir) revealed that five of them had a concentration-dependent inhibitory effect on CGamF accumulation in SCRHs, with IC50 values between 0.25 ± 0.07 and 43 ± 12 μM. The rank order for inhibition of CGamF accumulation in SCRHs was: ritonavir >> saquinavir > atazanavir > darunavir > amprenavir. Indinavir (up to 100 μM) did not alter CGamF accumulation, whereas nelfinavir solubility was limited to 10 μM. Taken together, these findings illustrate the utility of CGamF as a suitable probe (complementary to TC) for rapid in vitro determination of interaction potential with sodium-independent uptake mechanisms (likely Oatps) in rat liver.This publication has 28 references indexed in Scilit:
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