U-373 MG GLIOBLASTOMA AND IMR-32 NEUROBLASTOMA CELL-LINES EXPRESS THEDOPAMINE AND VESICULAR MONOAMINE TRANSPORTERS

The U-373 MG glioblastoma and the IMR-32 neuroblastoma cell lines were found to express the dopamine (DA) and vesicular monoamine transporte rs, using reverse transcriptase-polymerase chain reaction (RT-PCR), To further characterize the DA transporter, [H-3]GBR-12935 binding and [ H-3]DA uptake studies were performed, Specific binding of [H-3]GBR-129 35 to U-373 MG and IMR-32 cells is saturable as saturation experiments indicated, Scatchard analysis revealed two binding sites on U-373 MG as well as on IMR-32 cells, The high-affinity sites exhibited a K-D of 2.95 and 0.42 nM and a B-max of 6.4 and 0.83 fmol/mg protein for U-37 3 MG and IMR-32 cells, respectively, The low-affinity sites exhibited a K-D of 144 and 251 nM and a B-max of 37.5 and 119 fmol/mg protein fo r the same cells, respectively, The high-affinity binding of both type s of cells probably represents the ''classic'' DA uptake site identifi ed in other studies from human and rat striatal membranes or synaptoso mes, while the low-affinity binding may represent a mazindol-insensiti ve binding site (the ''piperazine acceptor site''), [H-3]DA uptake was 0.55 +/- 0.16 and 1.08 +/- 0.33 pmol/mg protein for U-373 MG and IMR- 32 cells, respectively. Since the DA transporter has been implicated a s an important site for drugs and toxins, the above-mentioned cell lin es may be a useful tool in the study of the mechanism of action of DA transporter modulating substances. (C) 1996 Wiley-Liss, Inc.