| Autor: |
Petit, A., Vaillancourt, C., Bellabarba, D., Lehoux, J. G., Gallo-Payet, N., Bélisle, S. |
| Zdroj: |
Journal of Receptor and Signal Transduction Research; June 1990, Vol. 10 Issue: 3-4 p205-215, 11p |
| Abstrakt: |
We studied the binding of [3H]-spiperone on human term placental membranes. This binding reached plateau level after 30 min incubation at 37°C and was reversed (t1/2 ∼ 5 min) by addition of an excess of unlabeled spiperone. Scatchard analysis of saturation experiments with increasing doses of [3H]-spiperone (0-25 nM) showed one class of high affinity binding sites with a dissociation constant (Kd) of 14 ± 2 nM and a maximal binding capacity (Bmax) of 222 ± 9 fmoles/mg protein. The affinity of 5 competitors was determined in competitive binding assays. The D2-dopamine antagonists were the most potent inhibitors: Ki for spiperone and haloperidol were 8 ± 2 and 56 ± 22 nM respectively. Dopamine inhibited [3H]-spiperone binding with a Ki of 570 ± 50 μM whereas Schering 23390 (D1 antagonist) and propranolol (β-adrenergic antagonist) were without effect. The binding was also inhibited by 100 μM GTPγS (38 ± 8% inhibition), indicating that the dopamine receptor is coupled with a GTP binding protein. These results demonstrate for the first time the presence of D2-dopamine receptors in human placenta. |
| Databáze: |
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