Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.64 (MPP)
 1,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human embryonic kidney 293 (HEK-293) cells stably transfected with the human serotonin (5-HT) or dopamine transporter (hSERT, hDAT), or the rat GABA transporter GAT-1 were incubated with saturating concentrations of transporter substrates (hSERT: [(3)H]5-HT, [(3)H]N-methyl-phenyl-pyridinium (MPP+); hDAT: [(3)H]dopamine, [(3)H]MPP(+); rGAT: [(3)H]GABA). Uptake velocities decreased significantly over time for [(3)H]5-HT and [(3)H]dopamine (already visible at 1 min), but not for [(3)H]MPP(+) or [(3)H]GABA. In efflux experiments cells were preloaded and substrate diffusion into the medium was studied following the addition of appropriate uptake inhibitors. Fractional effluxes were (% min(-1)) 1.27, 0.72, 0.27 and 0.08 for [(3)H]5-HT, [(3)H]dopamine, [(3)H]MPP(+) and [(3)H]GABA, respectively. The results suggest that in uptake experiments the more lipophilic substrates [(3)H]5-HT and [(3)H]dopamine leave the cells by diffusion already after a short time (1 min) of accumulation.
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PMID:Substantial loss of substrate by diffusion during uptake in HEK-293 cells expressing neurotransmitter transporters. 1151 69