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Omega-conotoxin-MVIID blocks an omega-conotoxin-GVIA-sensitive, high-threshold Ca2+ current in fish retinal ganglion

T Tabata1, B M Olivera, A T Ishida

  • 1Section of Neurobiology, Physiology, and Behavior, University of California, Davis 95616, USA.

Neuropharmacology
|May 1, 1996
PubMed

Insights

Omega-conotoxin-MVIID (omega-CTx-MVIID) reduces calcium channel currents in goldfish retinal cells. This peptide may target a novel type of calcium channel not previously identified.

Area of Science:

  • Neuroscience
  • Pharmacology
  • Cell Physiology

Background:

  • Calcium channels are crucial for neuronal function, including in retinal ganglion cells.
  • Conus peptides are potent modulators of various ion channels, including calcium channels.

Purpose of the Study:

  • To investigate the effects of omega-conotoxin-MVIID (omega-CTx-MVIID) on calcium (Ca2+) currents in goldfish retinal ganglion cells.
  • To characterize the specific type of calcium channels targeted by omega-CTx-MVIID.

Main Methods:

  • Voltage-clamp electrophysiology was used to measure Ca2+ current amplitude.
  • Goldfish retinal ganglion cells were utilized as the experimental model.
  • Pharmacological agents including omega-CTx-MVIID, omega-CTx-GVIA, BAY-K-8644, Ni2+, and omega-Aga-IIIA were applied sequentially.

Main Results:

  • Omega-conotoxin-MVIID (omega-CTx-MVIID) significantly reduced the amplitude of Ca2+ currents.
  • The effects of omega-CTx-MVIID were distinct from those of known calcium channel blockers and activators.
  • Experimental data suggest that omega-CTx-MVIID targets calcium channels that differ from T, L, N, P/Q, and R types.

Conclusions:

  • Omega-conotoxin-MVIID (omega-CTx-MVIID) is a potent inhibitor of Ca2+ currents in goldfish retinal ganglion cells.
  • These findings suggest the existence of a novel class of calcium channels modulated by omega-CTx-MVIID.

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