Differential Response of Human Serum Cholinesterase Types to an Inhibitor in Potato

Abstract

DIFFERENCES in the degree of inhibition of the activity of human serum cholinesterase (pseudocholinesterase) produced in vitro by the local anæsthetic dibucaine (nupercaine) make it possible to classify individuals into three distinct types according to the character of the cholinesterase present in their serum¹. These types are inherited, and are thought to be determined by a pair of allelic genes each of which is responsible for the synthesis of a distinct form of serum cholinesterase². The two types of homozygotes each have only one of these esterases in their serum, while the heterozygote is believed to have both of them in about equal amounts³. The classification of the three phenotypes may be achieved by a number of cholinesterase inhibitors besides dibucaine³. However, there also exist certain cholinesterase inhibitors, such as tetraethylpyrophosphonate and diisopropylfluorophosphonate which fail to discriminate between the three types, presumably because their mode of action is different³.