Automated Methods for Measuring Blood Cholinesterase: A Selective Comparison and a Novel Artifact

摘要

Cholinesterase activity units obtained by the more commonly used Levine automated systems are not valid, as the standard calibration curve for the method is determined with an artificial standard--glutathione, either in the presence or absence of the substrate acetylthiocholine. In the presence of the substrate, glutathione reacts with a substrate via a transesterification mechanism. The slope of the calibration curve, and consequently activity units, would vary, depending on the rate of interaction. In the absence of substrate, as glutathione dialyzes about one-third as rapidly as thiocholine, activity units are obtained that are approximately three times greater than valid values. An acceptable automated procedure is recommended. Utility and sensitivity of selected automated cholinesterase systems are discussed. (Author)