Effect of Under-nutrition and Alterations in Diet on the Choline Esterase Activity of Serum

Abstract

THE activity or ‘‘concentration of choline esterase in serum has been considered as a test of liver function¹, and an interest in this enzyme has been stimulated in recent years by the developments which took place in chemical warfare during the period of hostilities. So far, diet has not been implicated as one of the agents regulating the activity of either the ‘‘total or the ‘‘true choline esterase of serum ; but within the last eighteen months we have made numerous observations which show that the general level of nutrition and also certain changes of diet may exert a considerable influence. All the determinations of activity were made by measuring the carbon dioxide evolved by the enzyme in a Barcroft apparatus. The enzyme activity of a serum such that 1 c.c. liberates 1 c.mm. of carbon dioxide in 1 min. from the reaction mixture has been taken as unity. The ‘‘total choline esterase in serum was measured in the presence of 2· 5 per cent of acetyl choline chloride. This concentration of substrate is well above the optimum for true choline esterase, and the activity determined by this method is due mainly to ‘‘pseudo choline esterase. The ‘‘true choline esterase in the serum was determined by the method of Mendel, Mundell and Rudney².