Barium elicits reversal of low-concentration etorphine-induced decrease of potassium conductance in cultures of dissociated dorsal root ganglion neurons.
Etorphine is an non-selective opioid receptor agonist with very potent analgesic effect. Low concentrations (< nM) of most opioid receptor agonists decrease the K+ conductance (gK) in cultures of dissociated mouse dorsal root ganglion neurons regardless of the presence of Ba2+ However, low concentrations of etorphine, in contrast to all other opioids tested, decreased gK only in the absence of Ba2+. In the presence of Ba2+, pM-nM etorphine elicited dose-dependent increases, instead of decreases in gK. Higher concentrations of etorphine (> nM) not only increased gK but, in addition, appreciably increased a delayed-onset inward Ca2+ current during pulsed depolarization regardless of the presence of Ba2+.
Fan
S
S
Dept. of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Crain
S M
SM
D000818:Animals; D001464:Barium / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D005048:Etorphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005333:Fetus; D005727:Ganglia, Spinal / Q000502:physiology*; D007700:Kinetics; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*
D015220:Calcium Channels; D015221:Potassium Channels; D001464:Barium; D005048:Etorphine; D011188:Potassium