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Omega-conotoxin CVID inhibits a pharmacologically distinct voltage-sensitive calcium channel associated with

David J Adams1, Amanda B Smith, Christina I Schroeder

  • 1School of Biomedical Sciences, The University of Queensland, Brisbane, Australia. dadams@mailbox.uq.edu.au

The Journal of Biological Chemistry
|November 21, 2002
PubMed

Insights

Omega-conotoxin CVID selectively inhibits a distinct voltage-sensitive calcium channel, likely a N-type (Ca(v)2.2) variant, crucial for neurotransmitter release in parasympathetic neurons. This finding advances understanding of neuronal signaling pathways.

Area of Science:

  • Neuropharmacology
  • Molecular Neuroscience
  • Ion Channel Physiology

Background:

  • Neurotransmitter release from preganglionic parasympathetic neurons is typically resistant to common calcium channel blockers.
  • Understanding the specific calcium channels involved is key to modulating neuronal communication.

Purpose of the Study:

  • To investigate the effects of omega-conotoxins on cloned voltage-sensitive calcium channels and nerve-evoked neurotransmitter release.
  • To identify specific calcium channel subtypes targeted by omega-conotoxins in preganglionic cholinergic nerves.

Main Methods:

  • Utilized Xenopus oocytes expressing cloned voltage-sensitive calcium channels (L-, N-, R-type).
  • Assessed depolarization-activated Ba(2+) currents through these channels.
  • Examined nerve-evoked neurotransmitter release from rat submandibular ganglia.

Main Results:

  • Omega-conotoxin CVID inhibited neurotransmitter release and N-type calcium channel currents.
  • Omega-conotoxin MVIIA showed no significant effect on these processes.
  • High-affinity inhibition by CVID was linked to a lysine residue at position 10, suggesting a specific interaction with an N-type (Ca(v)2.2) calcium channel variant.

Conclusions:

  • Omega-conotoxin CVID targets a pharmacologically distinct calcium channel involved in neurotransmitter release.
  • The targeted channel is likely a variant of the N-type (Ca(v)2.2) calcium channel.
  • Structural differences in omega-conotoxins influence their affinity for specific calcium channel subtypes.

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