Modulation of ligand-gated dopamine channels in Helix neurones

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13 Citations (Scopus)

Abstract

Dopamine gates a fast excitatory response in Helix C2 neurones. Whole cell, and multiple unitary dopamine-gated currents showed variable decay rates and desensitization properties, suggesting the presence of more than one channel type. Manipulation of internal free [Ca2+] by various procedures (external zero Ca2+ or 1 mM Co2+, prolonged depolarization, A23187, or flufenamic acid), affected both the amplitude and decay time for the response, and also suggested the presence of separate fast and slowly decaying components. Responses were prolonged by intracellular fluoride a Iron specific phosphatase inhibitor, and attenuated and shortened by the protein kinase inhibitors H7 and staurosporine, and the calmodulin inhibitor W7. Phorbol ester potentiated and prolonged the response and this effect was reversibly antagonized by the specific protein kinase C inhibitor chelerythrine. Different dopamine-activated unitary currents were distinguished in outside-out patches by conductance (5, 8, 12 and 15pS), rate of recovery from desensitization, and pattern of openings. Discrimination of slow and fast components of the response was possible with apomorphine, ADTN, and caffeine. Paradoxically the dopamine antagonists chlorpromazine and spiperone, but not dopamine itself, stimulated sustained activity of 5pS unitary currents which did not desensitize in outside-out patches. Modulation of different channels underlying the fast dopamine response by protein kinase C, and possibly other mechanisms, provides a potent means of controlling excitatory dopaminergic synaptic transmission.

Original languageEnglish
Pages (from-to)313-322
Number of pages10
JournalPflügers Archiv: European Journal of Physiology
Volume434
Issue number3
DOIs
Publication statusPublished - Jun 1997

Keywords

  • ligand-gated dopamine response
  • protein kinase C
  • phosphorylation
  • ION CHANNELS
  • HIPPOCAMPAL-NEURONS
  • APLYSIA NEURONS
  • PHOSPHORYLATION
  • RECEPTORS
  • CALMODULIN
  • CALCIUM
  • PHOSPHATASES
  • PLASTICITY
  • FAMILY

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