title: Identification of interspecies difference in efflux transporters of hepatocytes from dog, rat, monkey and human.
abstract: The large interspecies differences of hepatobiliary transport present a challenge for the allometric prediction of human biliary excretion for drug candidates primarily cleared via hepatobiliary secretion. In the present study, we determined the metabolic stabilities of common fluorescent substrates of hepatobiliary efflux transporters and developed a rapid efflux assay to determine the functional activities of MRP/Mrp, BCRP/Bcrp and P-gp in hepatocytes of four species. The specificities of transporter-mediated dye efflux were confirmed by selective transporter inhibitors. Among tested species, transporter-specific dye efflux kinetics was consistent between freshly isolated and cryopreserved hepatocytes. Hepatocyte elimination half-lives of MRP/Mrp substrates GS-MF and calcein were observed in the rank order of human>monkey>dog>rat. The fourfold higher MRP/Mrp substrate efflux rate of rat hepatocytes compared to human is likely due to the species-specific functional differences of MRP2/Mrp2 expressed on the canalicular membrane. We also observed efficient BCRP-mediated pheophorbide A (PhA) efflux by human and dog hepatocytes, while PhA extrusion in monkey and rat hepatocytes appeared limited. P-gp function measured by DiOC2(3) efflux was minimal in hepatocytes of all origins and no significant species differences were detected. Our results demonstrated marked differences in hepatocyte MRP/Mrp and BCRP/Bcrp activities across species, indicating that they may contribute to the species differences of in vivo hepatobiliary excretion. These results also suggest the potential utility of primary hepatocytes, either fresh or cryopreserved, as an in vitro model to predict interspecies differences in the biliary transport of MRP/Mrp and BCRP/Bcrp substrates.
authors.affiliation: Department of Pharmacokinetics, Pfizer Global Research & Development, St. Louis, MO, USA.
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.forename: Haodan
authors.initials: H
authors.lastname: Yuan
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.forename: Guotao
authors.initials: G
authors.lastname: Song
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.forename: Mike
authors.initials: M
authors.lastname: Baratta
authors.forename: Fengmei
authors.initials: F
authors.lastname: Hua
authors.forename: Archie
authors.initials: A
authors.lastname: Thurston
authors.forename: Joanne
authors.initials: J
authors.lastname: Wang
authors.forename: Yurong
authors.initials: Y
authors.lastname: Lai
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000818:Animals; D001646:Bile / Q000378:metabolism; D002232:Carbocyanines / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics*; D002469:Cell Separation; D015925:Cryopreservation; D004285:Dogs; D005260:Female; D005452:Fluoresceins / Q000378:metabolism; D005456:Fluorescent Dyes; D006207:Half-Life; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008252:Macaca fascicularis; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002232:Carbocyanines; D002352:Carrier Proteins; D005452:Fluoresceins; D005456:Fluorescent Dyes; C081554:3,3'-diethyloxacarbocyanine; C007740:fluorexon