Four enzymes related to specific cell functions were ayed in rat sciatic nerve injury by crush (cr) or crush and ligation (cr-lig) after 2 , 7, and 15 days in situ. Enzyme activities in segments of sciatic nerve proximal and distal to the injury were compared to those in corresponding segments of the coritralateral nerve. Choline acetyltransferase (CAT) activity in the distal portion decreased by 65 % for cr and almost to zero for cr-lig by day 7, while in the proximal portions CAT decreased to 70% of control values by 7 days and to 50% at I5 days after cr-lig.
Thc activity of thc Schwann cell-myclin-associated enzymc 2',3'-cyclic nucleotide phosphohydrolase (CNP) decreased slowly distal to the injury. Distal to both types of in.jury the lysosomal enzyme beta^ glucuronidase (GLR) increased six-to eightfold by 15 days. Proximal to injury GLR also increased (P cr X 2.5, P cr-lig x 5 ) but the peak proxiinally was attained by day 7. Despite interruption of axonally transported enzymes, the activities of the metabolic enzyme creatine kinase (CK) increased distal to in.jury apparently reflecting changes in the functions of the Schwann cells. The loss of metabolic enLynies from the axonal compartment niay be cornpletely obscured by reciprocal changes in the nonncuronal compartments if thc activity is prcsent in both compartments.