Abstract

Sympathetic nerves to the cat spleen and vas deferens were crushed distal to the ganglion and reappearance of norepinephrine (NE) was estimated chemically and by fluorescence microscopy in the nerves and organs at different times. Histologic studies of the hypogastric nerves showed that NE accumulated proximal to the crush within a day. fluorescent fibers distal to the crush began to appear after two weeks, and they were distinctly present after 4 weeks. Regeneration of postganglionic sympathetic nerves to the spleen was assessed by reappearance of endogenous NE, restoration of function as judged by the amount of NE released by nerve stimulation and ability of the spleen to remove infused NE. Severe depletion (80-90%) occurred within 3 to 5 days after constriction. Partial recovery began within 4 to 8 weeks. Recovery was nearly 20% in 50 to 100 days. 50% in 100 to 150 days and almost complete in 180 days. Recovery of NE output in response to nerve stimulation was somewhat faster initially than the recovery of NE stores. The ability to remove infused NE was also related to regeneration of sympathetic nerves