title: Use of canalicular membrane vesicles (CMVs) from rats, dogs, monkeys and humans to assess drug transport across the canalicular membrane.
abstract: BACKGROUND
  A novel application of a Ultrafree filter cartridge/centrifugation method was evaluated to determine uptake in canalicular membrane vesicles (CMVs) from SD rats, beagle dogs, cynomolgus monkeys (common safety species in the pharmaceutical industry) and humans to assess biliary transport.
  
  
  METHODS
  CMVs prepared from fresh livers of rats, dogs, monkeys and humans (four donors) were characterized for enrichment, basolateral and Golgi contamination and orientation. The presence of MRP2 and p-glycoprotein (P-gp) were confirmed by Western blots. Uptake of [3H]-leukotriene C4 (LTC4) and [3H]-estradiol-17beta-d-glucuronide (E2-Gluc) was determined at a low substrate concentration and/or by kinetic measurements (K(m) and V(max)). Correlation of in vitro data with in vivo findings was achieved by determining the biliary clearance of E2-Gluc in rats after a single i.v. dose and with literature in vivo data for LTC4.
  
  
  RESULTS
  CMVs were highly enriched and minimally contaminated based on marker enzyme activities. Uptake clearance among different species varied by approximately ten-fold (rat > dog = human > monkey) for LTC4 and less than two-fold for E2-Gluc. The lower uptake of LTC4 by human than rat CMVs may be attributed to a higher Km value for human than rat CMVs. Uptake of LTC4 or E2-Gluc by human CMVs showed little inter-subject variability (2-5-fold). Differences in in vitro uptake clearance (10-fold) between LTC4 and E2-Gluc in rat CMVs seemed to correlate with differences in their biliary clearance (4-fold) in rats, consistent with LTC4 and E2-Gluc being a high and a low clearance substrate, respectively.
  
  
  CONCLUSIONS
  A novel application of a Ultrafree filter cartridge/centrifugation method was developed to determine uptake in CMVs from different preclinical animal safety species and humans, and may represent a useful approach to study the mechanism of biliary excretion during drug discovery and development.
authors.affiliation: Drug Safety and Metabolism, Wyeth Research RS3250, 500 Arcola Road, Collegeville, PA 19426, USA. shillia@wyeth.com
authors.forename: A D
authors.initials: AD
authors.lastname: Shilling
authors.forename: F
authors.initials: F
authors.lastname: Azam
authors.forename: J
authors.initials: J
authors.lastname: Kao
authors.forename: L
authors.initials: L
authors.lastname: Leung
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D000328:Adult; D000818:Animals; D001646:Bile / Q000378:metabolism; D001648:Bile Canaliculi / Q000201:enzymology / Q000378:metabolism*; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D002498:Centrifugation / Q000295:instrumentation / Q000379:methods; D004285:Dogs; D004353:Drug Evaluation, Preclinical; D004958:Estradiol / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D005260:Female; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D017997:Leukotriene C4 / Q000493:pharmacokinetics; D008099:Liver / Q000166:cytology*; D008252:Macaca fascicularis; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008875:Middle Aged; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D013379:Substrate Specificity
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004958:Estradiol; D017997:Leukotriene C4; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C000715087:ABCC2 protein, human; C025483:estradiol-17 beta-glucuronide