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 ac ting at mu -opioid receptors activated a different 130-pS channel. Clonidin e's effects were largely antagonized by the alpha (2)-adrenoceptor antagoni st idazoxan, but were poorly mimicked by agmatine. These results partially contradict the prevailing hypothesis that alpha (2) and opioid receptors ac t through the same ion channel transduction pathways. (C) 2001 Elsevier Sci ence B.V. All rights reserved.