Changes in nerve and muscle produced by long-term nerve ligation

The long-term effects of constricting ligatures applied to the sciatic nerves of neonatal rats were examined. The nerves showed a decrease in diameter below the ligature but no accumulation of either SDH or AChE. The muscle innervated showed predominately high levels of SDH, mATPase, phosphorylase and glycogen. Following removal of the ligatures, the nerves were similar in size above and below the ligature, and the corresponding muscles showed an increased number of fibers with decreased SDH activity. Although mATPase, PAS and phosphorylase activities remained high, groups of lightly staining fibers were evident with the mATPase reaction. Long-term nerve ligation appears to produce changes in axonal size rather than in the fast component of axoplastic flow. Furthermore, the changes produced in muscle histochemistry by nerve ligation are closely related to changes in axonal size than to disturbances in flow.