TASK-3 is a potassium channel that is constitutively leaky, thus maintaining the resting membrane potential. TASK-3 can be opened by certain anaesthetics thus greatly reducing neuronal excitability. TASK-3 is not a classic cannabinoid receptor but its activity is modulated by cannabinoids. Since cannabinoids have a physiological effect on TASK-3 it is effectively a cannabinoid receptor.
http://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=520
http://en.wikipedia.org/wiki/KCNK9
TASK 3 is coexpressed with TASK 1 in cerebellar granule cells, locus coeruleus, motor neurons, pontine nuclei, some cells in the neocortex, habenula, olfactory bulb granule cells, and cells in the external plexiform layer of the olfactory bulb. TASK-3 channels are also expressed in the hippocampus; both on pyramidal cells and interneurons.
