Premium
5‐Hydroxytryptamine Uptake and Imipramine Binding Sites in Neurotumor NCB‐20 Cells
Author(s) -
Nakaki Toshio,
Roth Bryan L.,
Chuang DeMaw,
Costa Erminio
Publication year - 1985
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1985.tb04081.x
Subject(s) - imipramine , desipramine , clomipramine , mianserin , chemistry , pharmacology , fluoxetine , tricyclic , endocrinology , medicine , serotonin , antidepressant , biochemistry , biology , stereochemistry , hippocampus , receptor , alternative medicine , pathology
NCB‐20 cells (neuroblastoma × fetal Chinese hamster brain hybrids) are equipped with a [ 3 H]5‐hydroxytryptamine ([ 3 H]5‐HT) uptake system and [ 3 H]imipramine recognition sites. Approximately 80% of the radioactivity taken up by cells incubated with [ 3 H]5‐HT was identified with 5‐HT. [ 3 H]5‐HT uptake was temperature‐dependent, partially sodium‐dependent, saturable ( K m = 7.3 ± 0.6 μ M ; V max = 2.0 ± 0.6 pmol/min/mg), and inhibited by clomipramine, imipramine, fluoxetine, and desipramine, but not by iprindole, mianserin, or opipramol. Lineweaver‐Burk plots showed a competitive type of inhibition by imipramine and fluoxetine. [ 3 H]5‐HT uptake was not inhibited by nisoxetine or benztropine. [ 3 H]Imipramine binding sites had a K D of 12 ± 2 n M and a B max of 22 ± 7 pmol/mg protein. The binding was sodium‐sensitive although to a lesser extent than that found with brain membranes. Imipramine binding was displaced by tricyclic antidepressants with the following order of potency: clomipramine > imipramine > fluoxetine > desipramine ± iprindole = mianserin > opipramol. These results suggest that imipramine binding sites are present together with the 5‐HT uptake sites in NCB‐20 cells and that these sites interact functionally but are different biochemically.