Department of Neuroscience, Karolinska Institute, Stockholm, Sweden.
The histamine H(3) receptor mediates inhibitory responses in the nervous system. Here, we demonstrate the coupling of the human histamine H(3) receptor to G protein-coupled inward rectifier potassium (GIRK) channels in Xenopus oocytes, using voltage-clamp. The histamine H(3) receptor agonist (R)-alpha-methylhistamine increased GIRK currents with an EC(50) of 2.5 nM. The response to (R)-alpha-methylhistamine was inhibited by the specific antagonist/inverse agonist clobenpropit. GIRK channels represent a novel effector pathway for the histamine H(3) receptor, also suggesting the use of electrophysiology assays in histamine H(3) receptor drug screening, allowing for the resolution of G protein activation kinetics.