ISSN:
1573-904X
Keywords:
Caco-2 cell monolayer
;
culture age
;
cyclosporin A
;
P-glycoprotein
;
verapamil
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Purpose. To determine whether the expression and activity of the P-glycoprotein (P-GP) drug efflux pump vary with the culture age of Caco-2 cell monolayers. Methods. Caco-2 cell monolayers were grown for 3–27 days on tissue culture-treated Transwells. P-GP efflux function was determined by measuring transmonolayer fluxes of cyclosporin A (CsA) and verapamil, while P-GP expression level was evaluated by Western blot analysis using monoclonal antibody C219. Results. The apparent permeability coefficient (Papp) of CsA (0.5 µM) in the basolateral-to-apical (B → A) direction increased with culture age and was higher than the apical-to-basolateral (A → B) direction at all times. Net secretory Papp significantly increased from day 17 onward compared to that observed during day 3 through 13. Verapamil (100 µM) significantly inhibited CsA transport in the B → A direction from day 17 to 27, while elevating CsA transport in the A → B direction from day 6 to 27. Interestingly, the Papp of verapamil (0.5 µM) in the B → A direction was significantly higher than in the A → B direction from day 6 to 27, rendering increases in net secretory Papp of verapamil with culture age. Western analysis revealed that P-GP expression level was in the order of 4 weeks ≈ 1 week 〉 3 weeks 〉 2 weeks at equal loading of cell proteins. Conclusions. P-GP is continuously expressed throughout the culture period, but it may not be fully functional at an early age. Caco-2 cell monolayers of day 17 to 27 appear to be a good model to evaluate the functional role of P-GP in drug efflux.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1016005212640
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