| Autor: |
Wang, Lijuan C., Berfield, Janet L., Kuhar, Michael J., Carroll, F. Ivy, Reith, Maarten E.A. |
| Předmět: |
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| Zdroj: |
Naunyn-Schmiedeberg's Archives of Pharmacology; Sep2000, Vol. 362 Issue 3, p238-247, 10p |
| Abstrakt: |
Human dopamine transporters, stably expressed by human embryonic kidney-293 cells, were reacted with 3β-(3p-chlorophenyl)tropan-2β-carboxylic acid p-isothiocyanatophenylethyl ester (RTI-76) under varying conditions. Exposure to RTI-76 (1 µM) at 0°C, followed by extensive wash-out, reduced subsequent binding of the cocaine analog [3H]2β-carbomethoxy-3β-(4-fluorophenyl)tropane (WIN 35,428), which was caused by an increase in Kd in the absence of a Bmax change. Exposure to RTI-76 (50 nM–1 µM) at 37°C, however, caused concentration-dependent reductions in binding Bmax; increases in Kd were observed only at high levels of RTI-76 (0.5–1 µM). The reductions in Bmax are consonant with acylation of transporters, the increases in Kd with incomplete wash-out observed also for the amine precursor of RTI-76 which lacks the isothiocyanate group for irreversible binding and which did not lower Bmax at 37°C. Reductions in binding Bmax generated by varying concentrations of RTI-76 up to 300 nM at 37°C correlated with reductions in [3H]dopamine uptake Vmax on a one-to-one basis, with Km values showing a tendency towards a small reduction as a function of transporter inactivation, but the potency of WIN 35,428 in inhibiting uptake not showing a change. The results are discussed in the context of possible oligomeric assemblies of dopamine transporters carrying multiple recognition sites for cocaine analogs and dopamine. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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