Protein kinase C and intracellular calcium are required for amphetamine-mediated dopamine release via the norepinephrine transporter in undifferentiated PC12 cells.
The role of protein kinase C and intracellular Ca(2+) on amphetamine-mediated dopamine release through the norepinephrine plasmalemmal transporter in undifferentiated PC12 cells was investigated. The selective protein kinase C inhibitor chelerythrine completely inhibited endogenous dopamine release elicited by 1 microM amphetamine. Direct activation of protein kinase C increased dopamine release in a Ca(2+)-insensitive, imipramine-sensitive manner and the release was not additive with amphetamine. Exocytosis was not involved since these events were not altered by either deletion of extracellular Ca(2+) or reserpine pretreatment. Down-regulation of protein kinase C activity by long-term phorbol ester treatment resulted in a dramatic decrease in amphetamine-mediated dopamine release with no apparent effect on [(3)H]dopamine uptake. To more completely examine a role for Ca(2+), intracellular Ca(2+) was chelated in the cells. Depletion of intracellular Ca(2+) considerably decreased dopamine release in response to 1 microM amphetamine compared with vehicle-treated cells, but had no effect on the [(3)H]dopamine uptake. Thus, our results suggest that amphetamine-mediated dopamine release through the plasmalemmal norepinephrine transporter is highly dependent on protein kinase C activity and intracellular but not extracellular Ca(2+). Furthermore, protein kinase C and intracellular Ca(2+) appear to regulate [(3)H]dopamine inward transport and amphetamine-mediated outward transport of dopamine independently in PC12 cells.
Kantor
L
L
Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, Michigan, USA.
Hewlett
G H
GH
Park
Y H
YH
Richardson-Burns
S M
SM
Mellon
M J
MJ
Gnegy
M E
ME
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D004298:Dopamine / Q000378:metabolism* / Q000493:pharmacokinetics; D015536:Down-Regulation / Q000187:drug effects; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D007424:Intracellular Fluid / Q000378:metabolism; D050484:Norepinephrine Plasma Membrane Transport Proteins; D016716:PC12 Cells; D010673:Pheochromocytoma / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D027981:Symporters; D013572:Synaptic Vesicles / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D002352:Carrier Proteins; D020536:Enzyme Activators; D050484:Norepinephrine Plasma Membrane Transport Proteins; C493226:Slc6a2 protein, rat; D027981:Symporters; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D000661:Amphetamine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D004298:Dopamine