Opioid peptides selective for mu- and delta-opiate receptors reduce calcium-dependent action potential duration by increasing potassium conductance.
We suggest that both mu- and delta-opiate receptors on dorsal root ganglion neuron somata are coupled to voltage- and/or calcium-dependent potassium channels since opioid peptide decreases of calcium-dependent action potential duration were: (1) not associated with a change of resting membrane potential or conductance; (2) accompanied by an increase in action potential after-hyperpolarization, and (3) blocked by intracellular injection of the potassium channel blocker cesium [18]. In contrast, norepinephrine [4] and cadmium [9], which have been reported to act on voltage-dependent calcium rather than potassium channels, shortened action potential duration and decreased after-hyperpolarization amplitude, an action not blocked by intracellular iontophoresis of cesium.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D004553:Electric Conductivity; D004723:Endorphins / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D005727:Ganglia, Spinal / Q000166:cytology; D007473:Ion Channels / Q000502:physiology*; D051379:Mice; D009474:Neurons / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D011957:Receptors, Opioid / Q000378:metabolism*; D013997:Time Factors
D004723:Endorphins; D007473:Ion Channels; D011957:Receptors, Opioid; D002104:Cadmium; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine