The proximity of Kir2.3 to synaptic inputs suggests that they hold the dendritic membrane potential near the potassium equilibrium potential, dampening responsiveness to excitatory inputs. Closure of these channels by M1 receptor activation enhances integration of EPSPs in striatopallidal neurons[27]. The opening of Kir2 channels depends on membrane lipid phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2). M1 receptor activation reduces channel opening by activating PLC and lowering membrane PtdIns(4,5)P2 (PIP2) levels.
