Morphine and clonidine activate different K+ channels on rat amygdala neurons.
In cell-attached patch-clamp recordings from freshly dissociated neurons of the rat amygdalohippocampal area, clonidine principally activated a 95-pS (picosiemens) inwardly rectifying K+-permeable channel, whereas morphine acting at mu-opioid receptors activated a different 130-pS channel. Clonidine's effects were largely antagonized by the alpha(2)-adrenoceptor antagonist idazoxan, but were poorly mimicked by agmatine. These results partially contradict the prevailing hypothesis that alpha(2) and opioid receptors act through the same ion channel transduction pathways.
Department of Pharmaceutical Sciences, Northeastern University, 211 Mugar Building, 360 Huntington Avenue, Boston, MA 02115, USA.
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Murphy
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Freedman
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000679:Amygdala / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D019329:Idazoxan / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009020:Morphine / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects* / Q000502:physiology; D051381:Rats
D000317:Adrenergic alpha-Antagonists; D000700:Analgesics; D015221:Potassium Channels; D009020:Morphine; D003000:Clonidine; D019329:Idazoxan