TY - JOUR T1 - Demonstration of the Activity of P-glycoprotein by a Semi-automated Fluorometric Method JF - Anticancer Research JO - Anticancer Res SP - 2173 LP - 2177 VL - 29 IS - 6 AU - GABRIELLA SPENGLER AU - MIGUEL VIVEIROS AU - MARTA MARTINS AU - LILIANA RODRIGUES AU - ANA MARTINS AU - JOZSEF MOLNAR AU - ISABEL COUTO AU - LEONARD AMARAL Y1 - 2009/06/01 UR - http://ar.iiarjournals.org/content/29/6/2173.abstract N2 - Background: We have developed a semi-automated fluorometric method that utilizes ethidium bromide (EB), a common substrate of bacterial efflux pumps. The method is sufficiently sensitive to characterize the efflux pump systems of bacteria. Because EB is also recognized and extruded by ATP-binding cassette (ABC) transporters and these have similarity to P-glycoprotein (P-gp), the method has been extended for the evaluation of agents that can inhibit the extrusion of EB on a real-time basis by mouse lymphoma cells containing the human ABCB1 (mdr1) gene. Materials and Methods: Monitoring of uptake and extrusion of EB was assessed using the Rotor-Geneā„¢ 3000 (Corbett Research) under different conditions. Results: Whereas extrusion of EB took place readily, the addition of known inhibitors of efflux pumps (verapamil, reserpine) caused retention of EB. Conclusion: This method is inexpensive and allows the detection of neoplastic cells with increased efflux activity as well as the screening of large numbers of compounds for inhibition of the P-gp. ER -