THE ULTRASTRUCTURAL LOCALIZATION OF CHOLINESTERASE ACTIVITY IN THE SCIATIC NERVE OF THE RAT

Abstract

Ultrastructural localization of cholinesterase activity was demonstrated in rat sciatic nerve using thiocholine esters as substrate. This enzymatic activity was limited to axons, where it was located on limiting axonal membranes, and on axonal vesicles of all unmyelinated and some myelinated nerve fibers. No accentuation of activity was present at nodes of Ranvier. The use of acetyl, propionyl and butyrylthiocholine as substrate resulted in decreasing amounts of end product precipitate, respectively. The cholinesterase activity was sensitive to heat, resistant to N-ethyl maleimide, and inhibited byeserine, DFP, E600, RO2-1250 and BW 62C47. Studies of specific inhibition sensitivities and substrate preferences suggested that the axonal cholinesterase of rat sciatic nerve is a specific acetylcholinesterase which is relatively homogeneous.