Neuron
Volume 6, Issue 1, January 1991, Pages 13-20
Journal home page for Neuron

Article
Activation of μ opioid receptors inhibits transient high- and low-threshold Ca 2+ currents, but spares a sustained current

https://doi.org/10.1016/0896-6273(91)90117-IGet rights and content

Abstract

Opioids and opiates decrease the duration of action potentials and the amount of neurotransmitter released from sensory neurons. The μ-type opioid receptor, the binding site for morphine, is thought to act exclusively on K+ channels. Here, we show that activation of the μ receptor inhibits Ca s+ channels in rat sensory neurons; the effect is blocked by a μ antagonist and is not mimicked by κ or S receptor agonists. Both low-threshold (T-type) and high-threshold Ca 2+ currents are partially suppressed. ω-Conotoxin-sensitive and ω-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.

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