Localization of Acetylcholinesterase Activity in the Mouse Heart.

The electron microscopic localization of the acetylcholinesterase (AChE) activity in the mouse heart was studied by the method of Tago et al. (1986). The results showed deposition of reaction product only in nerve elements: some neurons of the intrinsic atrial ganglia and atrial and ventricular nerve fibers. The AChE activity was particularly localized in the synaptic clefts. In contrast with previous reports describing the existence of “internal” ChE, no activity was detected within myocardial cells.