caa a22 4500 469078758 CHVBK 20180323132943.0 cr unu---uuuuu 170328e19920801xx s 000 0 eng 10.1007/BF00165297 doi (NATIONALLICENCE)springer-10.1007/BF00165297 The extraneuronal transport mechanism for noradrenaline (uptake2) avidly transports 1-methyl-4-phenylpyridinium (MPP+) [Elektronische Daten] [H. Russ, M. Gliese, J. Sonna, E. Schömig] Summary: The corticosterone-sensitive extraneuronal transport mechanism for noradrenaline (uptake2) removes the neurotransmitter from the extracellular space. Recently, an experimental model for uptake2 has been introduced which is based on tissue culture techniques (human Caki-1 cells). The present study describes some properties of uptake2 in Caki-1 cells and introduces a new substrate, i.e., 1-methyl-4-phenylpyridinium (MPP+). Experiments on Caki-1 cells disclosed disadvantages of tritiated noradrenaline as substrate for the investigation of uptake2. The initial rate of 3H-noradrenaline transport [kin = 0.58 μl/(mg protein · min)] was low compared with other cellular transport systems and intracellular noradrenaline was subject to rapid metabolism (kO-methylation = 0.54 min−1). The neurotoxin MPP+ was found to be a good substrate of uptake2. Initial rates of specific 3H-MPP+ transport into Caki-1 cells were saturable, the Km being 24 μmol/l and the Vmax being 420 pmol/(mg protein · min). The rate constant of specific inward transport was 34 times higher [19.6 μmol/l (mg protein · min)] than that of 3H-noradrenaline. The ratio specific over non-specific transport was considerably higher for 3H-MPP+ (12.6) than for 3H-noradrenaline (3.0). 3H-MPP+ transport into Caki-1 cells was inhibited by various inhibitors of uptake2. The highly significant positive correlation (p < 0.001, r = 0.986, n = 7) between the IC50's for the inhibition of the transport of 3H-noradrenaline and 3H-MPP+, respectively, proves the hypothesis that MPP+ enters Caki-1 cells via uptake2. 3H-MPP+ is taken up via uptake2 not only by Caki-1 cells but also by the isolated perfused rat heart which is another established model of uptake2. Tritiated MPP+ is a new and convenient tool for the investigation of uptake2. The rate constant for inward transport, the factor of accumulation and the ratio specific over non-specific transport are considerably higher for 3H-MPP+ than for 3H-noradrenaline. In uptake studies with 3H-MPP+ inhibition of intracellular noradrenaline-metabolizing enzymes is not necessary. In tissues and tissue cultures which possess fewer uptake2 carriers than Caki-1 cells or the rat heart, the identification and characterization of uptake2 can be expected to be greatly facilitated by the use of 3H-MPP+. Springer-Verlag, 1992 Extraneuronal noradrenaline transport nationallicence Uptake2 nationallicence 1-Methyl-4-phenylpyridinium (MPP+) nationallicence Caki-1 cells nationallicence Noradrenaline nationallicence Russ H. Department of Pharmacology, University of Würzburg, Versbacherstrasse 9, W-8700, Wurzburg, Federal Republic of Germany aut Gliese M. Department of Pharmacology, University of Würzburg, Versbacherstrasse 9, W-8700, Wurzburg, Federal Republic of Germany aut Sonna J. Department of Pharmacology, University of Würzburg, Versbacherstrasse 9, W-8700, Wurzburg, Federal Republic of Germany aut Schömig E. Department of Pharmacology, University of Würzburg, Versbacherstrasse 9, W-8700, Wurzburg, Federal Republic of Germany aut Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 346/2(1992-08-01), 158-165 0028-1298 346:2<158 1992 346 210 https://doi.org/10.1007/BF00165297 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00165297 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Russ H. Department of Pharmacology, University of Würzburg, Versbacherstrasse 9, W-8700, Wurzburg, Federal Republic of Germany aut NATIONALLICENCE 700 1- Gliese M. Department of Pharmacology, University of Würzburg, Versbacherstrasse 9, W-8700, Wurzburg, Federal Republic of Germany aut NATIONALLICENCE 700 1- Sonna J. Department of Pharmacology, University of Würzburg, Versbacherstrasse 9, W-8700, Wurzburg, Federal Republic of Germany aut NATIONALLICENCE 700 1- Schömig E. Department of Pharmacology, University of Würzburg, Versbacherstrasse 9, W-8700, Wurzburg, Federal Republic of Germany aut NATIONALLICENCE 773 0- Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 346/2(1992-08-01), 158-165 0028-1298 346:2<158 1992 346 210 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer