[³H]Nisoxetine: a new radioligand for norepinephrine uptake sites in brain

[³H]Nisoxetine binds with high affinity (K_d = 0.7 nM) and selectivity to a homogenous population of sites associated with the uptake of norepinephrine. Specific [³H]nisoxetine binding to rat cortical homogenates was saturable, sodium-dependent and averaged 90% of total binding at its K_d concentration. Pretreatment with the neurotoxin DSP-4 resulted in 95% decrease in binding. [³H]Nisoxetine exhibits superior properties to radioligands previously used and appears to be the radioligand of choice for studies involving uptake sites for norepinephrine.