Activation of mu opioid receptors inhibits transient high- and low-threshold Ca2+ currents, but spares a sustained current

Neuron. 1991 Jan;6(1):13-20. doi: 10.1016/0896-6273(91)90117-i.

Abstract

Opioids and opiates decrease the duration of action potentials and the amount of neurotransmitter released from sensory neurons. The mu-type opioid receptor, the binding site for morphine, is thought to act exclusively on K+ channels. Here, we show that activation of the mu receptor inhibits Ca2+ channels in rat sensory neurons; the effect is blocked by a mu antagonist and is not mimicked by kappa or delta receptor agonists. Both low-threshold (T-type) and high-threshold Ca2+ currents are partially suppressed. omega-Conotoxin-sensitive and omega-conotoxin-insensitive, high-threshold Ca2+ currents are inhibited. The kinetic effect on high-threshold current is like that caused by diminished rest potential: the transient component is selectively lost, whereas the sustained component is spared.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
  • Amino Acid Sequence
  • Animals
  • Calcium Channels / drug effects
  • Calcium Channels / physiology*
  • Cells, Cultured
  • Electric Conductivity
  • Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
  • Enkephalin, D-Penicillamine (2,5)-
  • Enkephalins / pharmacology
  • Molecular Sequence Data
  • Mollusk Venoms / pharmacology
  • Naltrexone / analogs & derivatives
  • Naltrexone / pharmacology
  • Narcotic Antagonists
  • Pyrrolidines / pharmacology
  • Rats
  • Receptors, Opioid / drug effects
  • Receptors, Opioid / physiology*
  • Receptors, Opioid, delta
  • Receptors, Opioid, kappa
  • Receptors, Opioid, mu
  • omega-Conotoxin GVIA

Substances

  • Calcium Channels
  • Enkephalins
  • Mollusk Venoms
  • Narcotic Antagonists
  • Pyrrolidines
  • Receptors, Opioid
  • Receptors, Opioid, delta
  • Receptors, Opioid, kappa
  • Receptors, Opioid, mu
  • Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
  • Naltrexone
  • 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
  • beta-funaltrexamine
  • Enkephalin, D-Penicillamine (2,5)-
  • omega-Conotoxin GVIA