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Titolo:
CHARACTERIZATION OF THE REGIONAL INTESTINAL KINETICS OF DRUG EFFLUX IN RAT AND HUMAN INTESTINE AND IN CACO-2 CELLS
Autore:
MAKHEY VD; GUO AL; NORRIS DA; HU PD; YAN JS; SINKO PJ;
Indirizzi:
RUTGERS STATE UNIV,COLL PHARM,160 FRELINGHUYSEN RD PISCATAWAY NJ 08854 RUTGERS STATE UNIV,COLL PHARM PISCATAWAY NJ 08854
Titolo Testata:
Pharmaceutical research
fascicolo: 8, volume: 15, anno: 1998,
pagine: 1160 - 1167
SICI:
0724-8741(1998)15:8<1160:COTRIK>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
MULTIDRUG-RESISTANCE PROTEIN; BLOOD-BRAIN-BARRIER; P-GLYCOPROTEIN; MEMBRANE-VESICLES; ESTABLISHES MRP; LEUKOTRIENE C-4; ORAL ABSORPTION; TUMOR-CELLS; TRANSPORT; SECRETION;
Keywords:
INTESTINAL TRANSPORT KINETICS; DRUG EFFLUX; JEJUNUM; ILEUM; COLON; CACO-2 CELLS; VINBLASTINE SULFATE; VERAPAMIL HYDROCHLORIDE; ETOPOSIDE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
39
Recensione:
Indirizzi per estratti:
Citazione:
V.D. Makhey et al., "CHARACTERIZATION OF THE REGIONAL INTESTINAL KINETICS OF DRUG EFFLUX IN RAT AND HUMAN INTESTINE AND IN CACO-2 CELLS", Pharmaceutical research, 15(8), 1998, pp. 1160-1167

Abstract

Purpose. The aim of the present study was to investigate the transport kinetics of intestinal secretory processes in the jejunum, ileum andcolon of rats and humans and in Caco-2 cells, in vitro. Methods. Etoposide, vinblastine sulphate and verapamil hydrochloride were chosen asmodel substrates since they have been reported to undergo efflux in various other tissues. The concentration dependence, inhibition, directionality, temperature dependence, proton/sodium dependence, and ATP dependence of efflux were studied using side-by-side diffusion chambers and brush border membrane vesicles (BBMVs). Intestinal tissue from rats and humans and Caco-2 cells (passage no. 26) were used. Directional steady state effective permeabilities were calculated from drug appearance in the apical (AP) or basolateral (BL) chambers. Kinetic studies were carried out by investigating substrate efflux at concentrations ranging from 0.2 mu M to 1000 mu M Since substrate efflux may be a result of more than one transporter, the hybrid efflux Km (Michaelis-constant), Pc (carrier-mediated permeability), and Pm (passive permeability) were determined as a function of intestinal region. Inhibitor studies were performed using quinidine (0.2 mh I), a mixed inhibitor of P-glycoprotein (Pgp) and Multidrug Resistance-Associated Protein (MRP). and Leukotriene C-4 (100 nM), an inhibitor of MRP and the canalicular multispecific organic anion transporter (cMOAT). Temperature dependent efflux was determined by investigating the BL to AP transport at temperatures ranging from 3 degrees C to 37 degrees C. Energies of activation (Ea) were determined from an Arrhenius analysis. Sodium, proton, andATP dependence were determined using BBMVs. Immunoquantitation of Pgp, MRP and Lung Resistance Protein (LRP) in Caco-2 cells were carried out using Western blot analysis. Results. Active efflux of all substrates was observed in all regions of rat and human intestine and in Caco-2 cells. Directionality was observed with BL to AP transport exceedingAP to BL transport. The BL to AP/AP to BL permeability ratio, the efflux ratio, ranged from IA to 19.8. Ileal efflux was significantly higher (p < 0.001) than in other regions. Kinetic studies revealed that hybrid efflux Km values ranged from 4 to 350 mu M. In some cases, effluxwas not saturable due to the solubility limits of the compounds utilized in this study. In presence of inhibitors, efflux ratios approached1. BL to AP transport was temperature dependent in rat ileum for all substrates. Ea of intestinal efflux was found to be 11.6, 8.3, and 15.8 kcal/mole for etoposide, vinblastine and verapamil, respectively, suggesting an active, energy-dependent efflux mechanism. Substrate efflux was not sodium or proton dependent but was dependent on ATP Using Western blot analysis the presence of Pgp, MRP, and LRP was demonstratedin Caco-2 cells and the amount of each transport protein varied as a function of passage number. Conclusions. Using multiple putative efflux substrates, the current results demonstrate that intestinal efflux was regionally dependent, mediated by multiple efflux transporters, theKm's were in the micromolar range, and involved an energy dependent mechanism(s).

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Documento generato il 20/01/21 alle ore 15:39:54