ML297 is a potent activator of GIRK channels; it shows a preference for the GIRK1/GIRK2 subunit combination compared to GIRK1/GIRK4 and is inactive on GIRK2/GIRK3 and a number of other potassium channels. ML297 is a useful tool to selectively probe GIRK1/2 channels function in vitro and in vivo. These properties make ML-297 the first and only molecule of its type to selectively probe GIRK1-containing GIRKs and hence it enables the studying of the role of GIRK1-containing GIRKs in numerous normal and pathophysiological conditions¹.

G protein-gated inwardly rectifying potassium (GIRK) channels hyperpolarize neurons in response to the activation of many G-protein coupled receptors. They are members of the large super-family of inwardly rectifying K⁺ channels (K_ir), in which the inward current is significantly greater than the outward current. Their specific biochemical properties generate a slow inhibitory postsynaptic current that provides a sustained form of inhibition of neuronal activity².

GIRK channel activity has an important role in physiological responses, including pain perception and memory modulation. Moreover, abnormal GIRK function is implicated in altering neuronal excitability and cell death that may be important in the pathophysiology of human diseases such as epilepsy, Down’s syndrome, Parkinson’s disease and drug addiction. GIRK channels may therefore prove to be valuable new therapeutic targets for treating these health problems².

GIRK1-GIRK2 heterotetramers are believed to be the predominant form of GIRK channels expressed in brain³.