Receptor for octopamine. Octopamine (OA) is a neurotransmitter, neurohormone, and neuromodulator in invertebrates. This receptor induces a long lasting opening of voltage- independent chloride channels, a process which seems to involve protein phosphorylation but does not require either cAPK or PKC. The rank order of potency for agonists is p-synephrine > p-octopamine > xylometazoline > B-HT920 > norepinephrine = clonidine > epinephrine > p-tyramine > phenylephrine = oxymetazoline = mehoxamine = dopamine > serotonin > histamine. For antagonists, the rank order is rauwolscine = mianserin > phentolamine > chlorpromazine > spiperone > yohimbine > propanolol > alprenolol > prazosine > pindolol. Belongs to the G-protein coupled receptor 1 family.