Effects of aldehyde fixation and of preganglionic denervation on acetylcholinesterase and butyrocholinesterase of cat autonomic ganglia.

Fixation of cat stellate ganglia by perfusion in situ with cold 4% formaldehyde in Krebs-Ringer solution, followed by immersion in the same solution for 3 or 6 hr, produced inactivation of approximately one-half the acetylcholinesterase (AChE) and butyrocholinesterase (BuChE); after 21 hr, further inactivation occurred. Similar fixation with glutaraldehyde (1, 2 and 4%) inactivated over three-quarters of the AChE and BuChE at 3 hr. but there was little further loss after 21 hr. Following sectioning of the preganglionic trunk, the AChE activity of the cat superior cervical ganglion fell to approximately 20%, and BuChE fell to approximately 50%; this confirms an early report by Sawyer and Hollinshead, which has been questioned in part because of subsequent histochemical findings. The basis for the discrepancy is discussed, along with its bearing on the interpretation of histochemical observations in general.