title: The guinea-pig expresses functional CYP2C and P-glycoprotein: further validation of its usefulness in drug biotransformation/transport studies.
abstract: BACKGROUND
  The guinea-pig is an excellent animal model for studying cardiopulmonary physiology/pharmacology. Interestingly, it also possesses a number of drug-metabolizing enzymes found in humans, such as CYP1A, CYP2D and CYP3A.
  
  
  OBJECTIVE
  To evaluate the hypothesis that the guinea-pig also expresses a functional CYP2C drug-metabolizing enzyme and the P-glycoprotein (P-gp) drug transporter in various tissues.
  
  
  METHODS
  cDNAs encoding CYP2C and P-gp were obtained from guinea-pig liver or small intestine and sequenced. Western blotting was performed to confirm the expression of CYP2C and P-gp. The functional enzymatic activity of guinea-pig CYP2C was evaluated with microsomal preparations using diclofenac and tolbutamide as specific drug substrates in HPLC analyses. To further study both P-gp and CYP2C functional activities, the guinea-pig ABCB1/MDR1 and CYP2C genes were cloned. The recombinant plasmids were then transfected in HEK293 (human embryonic kidney) cells and either calcein-acetoxymethyl ester (AM) accumulation assays or 14,15-EET/DHET formation experiments were performed to evaluate either P-gp transport activity or CYP2C epoxygenase activity, respectively. The guinea-pig tissue distribution of P-gp was studied by Western blotting.
  
  
  RESULTS
  Functional expression of CYP2C was demonstrated in guinea-pig liver microsomal preparations. CYP2C-mediated biotransformation of diclofenac and tolbutamide were shown. Expression of P-gp protein was detected in guinea-pig liver and small intestine. Functional activity of guinea-pig P-gp was demonstrated in ABCB1/MDR1-transfected cells. GP-CYP2C-transfected cells also showed functional epoxygenase activity.
  
  
  CONCLUSIONS
  The guinea-pig expresses functional CYP2C and P-gp, thus suggesting its usefulness for further validating data obtained with other animal models in drug biotransformation/transport studies.
authors.affiliation: Faculté de Pharmacie, Université Laval, Québec, QC, Canada; Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC, Canada.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Hasibu
authors.forename: Dany
authors.initials: D
authors.lastname: Patoine
authors.forename: Sylvie
authors.initials: S
authors.lastname: Pilote
authors.forename: Benoit
authors.initials: B
authors.lastname: Drolet
authors.forename: Chantale
authors.initials: C
authors.lastname: Simard
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D001711:Biotransformation; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D004008:Diclofenac / Q000494:pharmacology; D006168:Guinea Pigs; D057809:HEK293 Cells; D006801:Humans; D006900:Hydroxylation; D007421:Intestine, Small / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D014044:Tolbutamide / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; C400322:cytochrome P-450 CYP2C subfamily; D004008:Diclofenac; D003577:Cytochrome P-450 Enzyme System; D014044:Tolbutamide
keywords: CYP2C; P-glycoprotein; drugs; guinea-pig