Abstract
Serum cholinesterase activity were determined by a kinetic method using acetylcholine as substrate (AK method) with a Hitachi 736 autoanalyzer system. Measurement of serum cholinesterase by AK method were linear from 0 to 8000IU/L. The coeffient of variation in within-run was 0.99% for a sample with cholinesterase activity of 3305IU/L, and 0.92% for a sample with activity of 6803IU/L (n=10). The CV in between-run was 1.2% for a sample with activity of 3295IU/L (n=7). Neither ascorbate (up to 50mg/dl) nor bilirubin (up to 40mg/dl) nor hemoglobin (up to 500mg/dl) did interfere with the measurement by this method.
The serum cholinesterase activities of both the human being and several kinds of animals, such as dog, rat, rabbit and monkey, as determined by the pH change (ΔpH) produced by a reaction using acetylcholine as substrate were correlated well with those determined by AK method, but not well as a whole with those measured by a method using o-toluoylcholine as substrate. Some control serum samples show abnormally high activities of cholinesterase when determined by AK method, as compared with the indicated value. Because acetate intereferes with measurement of cholinesterase activity by AK method, these sample sera may be spiked with an acetate solution by the manufacturer without notice.
