Mechanism of Norepinephrine Binding

Abstract

A NUMBER of sympathomimetic amines chemically related to norepinephrine (Fig. 1), which have either a catechol or β-hydroxyl group, can be stored in the vesicles of sympathetic nerves1. Octopamine, which lacks only the m-hydroxyl group of norepinephrine, is released by nerve stimulation2, and is depleted by drugs which deplete norepinephrine3. Although bound to particles with similar sedimentation characteristics as those which store norepinephrine4,5, octopamine appears to be stored mainly in a compartment which has a rapid turnover.