title: Dopamine transporters depolarize neurons by a channel mechanism.
abstract: Neurotransmitter transporters generate larger currents than expected if one assumes fixed stoichiometry models. It remains controversial, however, whether these depolarizing currents arise from high density and rapid turnover rates of a classical transporter, or whether transporters exhibit bona fide channel behavior. Although heterologously expressed transporters show single-channel behavior and noise analysis in native cells strongly suggests channel behavior, no directly observed single-channel events associated with transporters have been reported thus far in native cells. We describe single-channel events arising directly from the Caenorhabditis elegans dopamine transporter (DAT-1) as evidenced by DA-induced channel activity blocked by a high-affinity DAT-1 inhibitor, increased channel activity in neurons that overexpress DAT-1, and loss of channels in dat-1 knockout neurons. Our data indicate that authentic transporter channels underlie depolarizing whole-cell currents. Thus, DA transporters not only transport DA but also exhibit a channel mode of conduction that directly modulates membrane potential and neuronal function.
authors.affiliation: Department of Pharmacology and Center of Neuroscience, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, USA. lucia.carvelli@vanderbilt.edu
authors.forename: Lucia
authors.initials: L
authors.lastname: Carvelli
authors.forename: Paul W
authors.initials: PW
authors.lastname: McDonald
authors.forename: Randy D
authors.initials: RD
authors.lastname: Blakely
authors.forename: Louis J
authors.initials: LJ
authors.lastname: DeFelice
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D018509:DNA, Helminth / Q000235:genetics; D004298:Dopamine / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008564:Membrane Potentials; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D018509:DNA, Helminth; D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D004298:Dopamine