Activation of inwardly rectifying potassium channels (GIRK1) by co-expressed rat brain cannabinoid receptors in Xenopus oocytes.

The neuronal cannabinoid receptor clone was expressed of saturable [3H]WIN 55,212-2 binding sites. Co-expression of the cannabinoid receptor with cRNA coding for the G-protein-gated inwardly rectifying K+ channel (GIRK1) resulted in oocytes exhibiting large inward K+ currents in response to the cannabinoid agonist WIN 55,212-2. The activation of the potassium current by WIN 55,212-2 was dose-dependent with an EC50 of 630 nM. These results suggest that activation of inwardly rectifying K+ channels may be an additional effector mechanism for brain cannabinoid receptors.