Subject Area物理化学
A Kinetic Study of Rhodamine 123 Pumping by P-glycoprotein
Yang L(杨凌); Wang YL(王玉林); WilfredD.Stein
Conference NameThe 1st asia Pacific ISSX Meeting
Conference Date2006-5-24
Conference Place韩国
AbstractObjective: To understand the transport kinetics of P-glycoprotein with detail. Methods: We have developed a kinetic approach to study P-gp transport, based on the influx of Rhodamine 123 (Rho123), a much-used probe for P-gp. In order to avoid the complications in data analysis that can arise due to the self-quenching of Rho123 within the loaded cells, we introduce a method in which the drug sensitive cells are used to provide a calibration curve for the amount of Rho123 accumulated within the cells at any level of external probe (upper curve, figure A, below). This enables us to calculate, for the resistant cells (lower curve, in A), the relative amount of probe that has been pumped out of the cells. Results and conclusion: We use this to obtain a measure of the fraction of the probe that is pumped out of the cell, at any level of external Rho123 (Curve B in figure). It is from this fraction and its dependence on the level of external probe that we derive the kinetic data for Rho123 pumping. We confirm that P-gp is an effective efflux transporter of Rho123 and that there is co-operative interaction between Rho123 molecules (probably in pairs, the Hill number being 1.94+/- 0.32) as they bind to P-gp during efflux pumping. We estimate the apparent affinity of Rho123 for the pump’s binding sites as Km = 7.2 +/- 1.1 uM. Verapamil addition diminishes the rate of efflux pumping, with Ki = 1.1 uM, and does so in an un-competitive fashion. (Supported by the DUT-DICP scientific cooperation fund)
WOS IDWOS:000242406900252
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Cited Times:3[WOS]   [WOS Record]     [Related Records in WOS]
Document Type会议论文
Corresponding AuthorYang L(杨凌)
Recommended Citation
GB/T 7714
Yang L,Wang YL,WilfredD.Stein. A Kinetic Study of Rhodamine 123 Pumping by P-glycoprotein[C],2006:271/1.
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