Dopamine neuronal transport kinetics and effects of amphetamine.
The dopamine (DA) transporter (DAT) regulates DA neurotransmission by recycling DA back into neurons. Drugs that interfere with DAT function, e.g., cocaine and amphetamine, can have profound behavioral effects. The kinetics of DA transport by DAT in isolated synaptosomal or single cell preparations have been previously studied. To investigate how DA transport is regulated in intact tissue and to examine how amphetamine affects the DAT, the kinetics of DA uptake by the DAT were examined in tissue slices of the mouse caudate-putamen with fast-scan cyclic voltammetry. The data demonstrate that inward DA transport is saturable and sodium-dependent. Elevated levels of cytoplasmic DA resulting from disruption of vesicular storage by incubation with 10 microM Ro 4-1284 did not generate DA efflux or decrease its uptake rate. However, incubation with 10 microM amphetamine reduced the net DA uptake rate and increased extracellular DA levels due to DA efflux through the DAT. In addition, a new, elevated steady-state level of extracellular DA was established after electrically stimulated DA release in the presence of amphetamine, norepinephrine, and exogenous DA. These results from intact tissue are consistent with a kinetic model of the DAT established in more purified preparations in which amphetamine and other transported substances make the inwardly facing DAT available for outward transport of intracellular DA.
Jones
S R
SR
Howard Hughes Medical Institute, Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA.
Joseph
J D
JD
Barak
L S
LS
Caron
M G
MG
Wightman
R M
RM
D000662:Amphetamines / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism*; D002421:Caudate Nucleus / Q000187:drug effects / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D004558:Electric Stimulation; D017136:Ion Transport / Q000187:drug effects; D007700:Kinetics; D008297:Male; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D014179:Neurotransmitter Uptake Inhibitors / Q000494:pharmacology*; D010042:Ouabain / Q000494:pharmacology; D011699:Putamen / Q000187:drug effects / Q000378:metabolism; D012964:Sodium / Q000502:physiology
D000662:Amphetamines; D002352:Carrier Proteins; D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D014179:Neurotransmitter Uptake Inhibitors; C493215:Slc6a3 protein, mouse; D010042:Ouabain; D012964:Sodium; D004298:Dopamine