A variety of evidence indicates that [3H]desipramine can label neuronal norepinephrine uptake sites in brain membranes. Pretreatment of rat cerebral cortical membranes with 0.3 M KCl increases the ratio of high affinity to low affinity saturable [3H]desipramine binding. With this improved tissue preparation, we have confirmed our earlier observation that the high affinity [3H]desipramine bindin...