NASPM is a synthetic analog of Joro spider toxin that blocks GluR2-lacking, Ca2+-permeable AMPA receptors. The blocking effect of NASPM on these receptors is use and voltage-dependent. At -60 mV, NASPM can suppress current responses in kainate-induced type II neurons (which are typified by strong inward rectification and high permeability to Ca2+) with an IC50 value of 0.33 μM. However, at +40 mV, NASPM does not affect Ca2+-permeable AMPA receptors. NASPM has been shown to protect against ischemia-induced neuronal cell death by preventing influx of toxic levels of Ca2+ into injured neurons. This compound can be used to study the role of GluR2 subunits in calcium permeability of AMPA receptors.
