Modulation of calcium-activated potassium small conductance (SK) current in rat dopamine neurons of the ventral tegmental area.
Block of calcium-sensitive potassium SK current (gKCa([SK])) by apamin or bicuculline methiodide potentiates burst firing in dopamine neurons in the presence of N-methyl-D-aspartate (NMDA). The purpose of this study was to test the hypothesis that calcium entry through NMDA-gated channels can potentiate gKCa([SK]) in dopamine neurons in the ventral tegmental area. We used microelectrodes to record an outward tail current that was evoked by membrane depolarization under single-electrode voltage-clamp. Using bicuculline methiodide (50 microM) as a reversible inhibitor of gKCa([SK]), we found that NMDA (15 microM) reduced the peak amplitude of the outward tail current by 39%. Contrary to expectations, our results suggest that stimulation of NMDA receptors reduces the calcium-activated potassium gKCa([SK]), an effect that could facilitate NMDA-dependent burst firing.
Paul
Kush
K
Department of Neurobiology and Behavior, State University of New York Stony Brook, Stony Brook, NY 11794, USA. kush.paul@stonybrook.edu
Keith
Dove J
DJ
Johnson
Steven W
SW
D000818:Animals; D004298:Dopamine / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*; D024681:Potassium Channels, Calcium-Activated / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D051640:Small-Conductance Calcium-Activated Potassium Channels; D017557:Ventral Tegmental Area / Q000502:physiology*
D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D051640:Small-Conductance Calcium-Activated Potassium Channels; D004298:Dopamine