Electron Microscopic Localization of Acetylcholinesterase and Nonspecific Cholinesterase at the Neuromuscular Junction by the Gold-Thiocholine and Gold-Thiolacetic Acid Methods

Abstract

By means of the gold-thiocholine (AuThCh) and gold-thiolacetic acid (AuThAc) methods, it has been demonstrated electron microscopically that acetylcholinesterase (AChE) is located at the prejunctional axoplasmic membrane and the postjunctional sarcoplasmic membrane, including the full lengths of its invaginations, at the motor end plate of mouse intercostal muscle. Nonspecific cholinesterase (ChE) is present in relatively low concentrations at the same sites, and in greater concentrations in the teloglial Schwann sheath cells.

The effect of voltage on the time course of end‐plate currents

“…The presence of a resistance in series with the end-plate membrane (resistance of the synaptic cleft, for example) is an important source of artifacts. Such artifacts arise because voltage drops across this series resistance produced by end-plate currents are not detected by the voltage Barrnett, 1962;Miledi, 1964;Davis & Koelle, 1967), the possibility exists that the hydrolytic action of these molecules could be influenced by membrane potential, and thus that the voltage sensitivity of ac could be mediated through acetylcholinesterase. On this hypothesis, hyperpolarization would slow the rate of acetylcholine hydrolysis by esterase, prolong transmitter action and thus lengthen the falling phase of the end-plate currents.…”

Electron Microscopic Demonstration of Cholinesterase in the Human Intercostal Muscle by an Indoxyl Acetate Esterase Method

“…In addition, a granular deposition of the endproduct was observed within the overstained junctional clefts as described by Barrnett (1, 2) and Davis and Koelle (7). In the rest part of the human intercostal muscle, no enzyme activity was observed in the present study, though Davis and Koelle (7) reported the activity of cholinesterase in Schwann cells, Barrnett (l, 2) observed acetylcholinesterase activity in synaptic vesicles in the axon terminals, Zacks and Blumberg (15,16) observed the enzyme reaction in the mitochondria in both the axon terminals and sarcoplasma and Bergman et al (4), Barrnett and Hagstrom (3), Karnovsky (8) and Miladic (13) indicated the activity in the sarcoplasmic reticulum in the intermyofibrillar spaces.…”

“…Cholinesterases have been demonstrated with several electron microscopic methods involving both metal capturing thiolacetic acid and thiocholine methods and azo dye methods (1)(2)(3)(4)(5)(6)(7)(8)(11)(12)(13). Although the former methods have their own hazards for the staining artifacts, for example a possible nonenzymatic reaction of lead salt, a question on the conversion technique to metal sulfide and large crystalline structure of the reaction product, it has been shown recently that aurous gold capturing method demonstrates excellently the localization of acetylcholinesterase and nonspecific cholinesterase (7).…”

“…Although the former methods have their own hazards for the staining artifacts, for example a possible nonenzymatic reaction of lead salt, a question on the conversion technique to metal sulfide and large crystalline structure of the reaction product, it has been shown recently that aurous gold capturing method demonstrates excellently the localization of acetylcholinesterase and nonspecific cholinesterase (7).…”

The fine structural localization of cholinesterases in the carotid body of the cat

“…The application oftechniques giving a finer grain reaction product, e.g. Davis & Koelle (1967) with correspondingly greater resolution would elucidate this important point.…”