The guinea-pig expresses functional CYP2C and P-glycoprotein: further validation of its usefulness in drug biotransformation/transport studies.
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.


CONCLUSION
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.
['Hasibu|Ibrahim|I|', 'Patoine|Dany|D|', 'Pilote|Sylvie|S|', 'Drolet|Benoit|B|', 'Simard|Chantale|C|']
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 D000818:Animals D001692:Biological Transport D001711:Biotransformation D003577:Cytochrome P-450 Enzyme System D004008:Diclofenac D006168:Guinea Pigs D057809:HEK293 Cells D006801:Humans D006900:Hydroxylation D007421:Intestine, Small D008099:Liver D008297:Male D008862:Microsomes, Liver D014044:Tolbutamide
guinea-pig CYP2C P-glycoprotein drugs