Norepinephrine release from nerve terminals within the rabbit superior cervical ganglion

Norepinephrine-3H (NE-3H) and its metabolic normetanephrine-3H were released from the superfused rabbit SCG incubated in tyrosine-3H in response to preganglionic stimulation. Neither dopamine-3H nor its metabolite, 3-methoxy-tyrosine could be detected in the superfusate from "control" or "nerve stimulated" tissues. Nerve stimulated NE-3H release a) was calcium dependent, b) had a stimulus threshold similar to that of C fibers, c) was not blocked by either 50 micromolar curare or 100 micromolar atropine, d) was abolished by chronic decentralization and e) was elicited by stimulation of both the cervical sympathetic and internal carotid nerves. These results suggest that there is a here-to-for undescribed, noradrenergic pathway which originates elsewhere in the sympathetic chain but terminates in the superior cervical ganglion.